UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  -------------

                                  SCHEDULE 13D
                                 (Rule 13d-101)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
            TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
                                  RULE 13d-2(a)

                    Under the Securities Exchange Act of 1934
                                (Amendment No. )*



                                 InfoSpace, Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)

                                  Common Stock
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    45678T201
--------------------------------------------------------------------------------
                                 (CUSIP Number)

                         Sandell Asset Management Corp.
                               40 West 57th Street
                                   26th Floor
                               New York, NY 10019
                   Attention: Richard Gashler, General Counsel
                                  212-603-5700

                                 With a Copy to:
                              Marc Weingarten, Esq.
                            Schulte Roth & Zabel LLP
                                919 Third Avenue
                               New York, NY 10019
                                  212-756-2000
--------------------------------------------------------------------------------
(Name, Address and Telephone Number of Person Authorized to Receive Notices and
                                 Communications)

                                  March 1, 2007
                               ------------------
             (Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box
[ ].

Note: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7 for other parties
to whom copies are to be sent.

                          (Continued on following pages)
                               (Page 1 of 13 Pages)

--------------------
* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page. The information required on the
remainder of this cover page shall not be deemed to be "filed" for the purpose
of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise
subject to the liabilities of that section of the Act but shall be subject to
all other provisions of the Act (however, see the Notes).





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 2 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Castlerigg Master Investments Ltd.
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              WC
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              British Virgin Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,523,443
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,523,443
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,523,443
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.8%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 3 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Sandell Asset Management Corp.
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              Cayman Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  2,771,204
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          2,771,204
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              2,771,204
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              8.8%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 4 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Castlerigg International Limited
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              British Virgin Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,523,443
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,523,443
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,523,443
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.8%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 5 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Castlerigg International Holdings Limited
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              British Virgin Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,523,443
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,523,443
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,523,443
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.8%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 6 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Castlerigg Global Select Fund, Limited
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              Cayman Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,247,761
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,247,761
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,247,761
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.0%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 7 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              CGS, Ltd.
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              WC
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              Cayman Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,247,761
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,247,761
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,247,761
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.0%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 8 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Castlerigg GS Holdings, Ltd.
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              Cayman Islands
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  1,247,761
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          1,247,761
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              1,247,761
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              4.0%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              CO
------------- -----------------------------------------------------------------




----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 9 of 13 Pages
----------------------------                        ----------------------------

------------- -----------------------------------------------------------------
     1        NAME OF REPORTING PERSON

              Thomas E. Sandell
------------- -----------------------------------------------------------------
     2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) |X|  (b) |_|
------------- -----------------------------------------------------------------
     3        SEC USE ONLY
------------- -----------------------------------------------------------------
     4        SOURCE OF FUNDS

              AF
------------- -----------------------------------------------------------------
     5        CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
              TO ITEMS 2(d) or 2(e)     |_|
------------- -----------------------------------------------------------------
     6        CITIZENSHIP OR PLACE OF ORGANIZATION

              Sweden
------------- -----------------------------------------------------------------
 NUMBER OF    7           SOLE VOTING POWER

   SHARES                 0
              ----------- -----------------------------------------------------
BENEFICIALLY  8           SHARED VOTING POWER

   OWNED                  2,771,204
              ----------- -----------------------------------------------------
  BY EACH     9           SOLE DISPOSITIVE POWER

 REPORTING                0
              ----------- -----------------------------------------------------
  PERSON      10          SHARED DISPOSITIVE POWER
                          2,771,204
   WITH
------------- ----------- -----------------------------------------------------
     11       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

              2,771,204
------------- -----------------------------------------------------------------
     12       CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
              SHARES |_|
------------- -----------------------------------------------------------------
     13       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 11

              8.8%
------------- -----------------------------------------------------------------
     14       TYPE OF REPORTING PERSON

              IN
------------- -----------------------------------------------------------------





----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 10 of 13 Pages
----------------------------                        ----------------------------

ITEM 1.       SECURITY AND ISSUER

     This statement on Schedule 13D relates to the common stock, par value
$0.0001 per share (the "Common Stock"), of InfoSpace, Inc., a Delaware
corporation (the "Issuer"). The principal executive offices of the Issuer are
located at: 601 108th Avenue NE, Suite 1200, Bellevue, Washington 98004.

ITEM 2.       IDENTITY AND BACKGROUND

     (a) The names of the persons filing this statement on Schedule 13D are
Castlerigg Master Investments Ltd., a British Virgin Islands company
("Castlerigg Master Investments"); Sandell Asset Management Corp., a Cayman
Islands exempted company ("SAMC"); Castlerigg International Limited, a British
Virgin Islands company ("Castlerigg International"); Castlerigg International
Holdings Limited, a British Virgin Islands company ("Castlerigg Holdings");
Castlerigg Global Select Fund, Limited, a Cayman Islands exempted company
("Castlerigg Global Select"); CGS, Ltd., a Cayman Islands exempted company
("CGS"); Castlerigg GS Holdings, Ltd., a Cayman Islands exempted company
("CGSH"); and Thomas E. Sandell ("Sandell"). Castlerigg Master Investments,
SAMC, Castlerigg International, Castlerigg Holdings, Castlerigg Global Select,
CGS, CGSH and Sandell are collectively referred to herein as the "Reporting
Persons". The filing of this statement on Schedule 13D and any future amendments
hereto, and the inclusion of information herein and therein, shall not be
construed as an admission that any of the Reporting Persons, for the purpose of
Section 13(d) of the Act or otherwise, is the beneficial owner of any shares of
Common Stock in which such person does not have a pecuniary interest.

     (b) The principal business address for each of Castlerigg Master
Investments, Castlerigg International and Castlerigg Holdings is c/o Citco Fund
Services (Curacao) N.V., Kaya Flamboyan 9, P.O. Box 812, Curacao, Netherlands
Antilles. The principal business address for Castlerigg Global Select, CGS and
CGSH is Walker House, P.O. Box 265GT, Mary Street, George Town, Grand Cayman,
Cayman Islands. The principal business address for each of SAMC and Sandell is
c/o Sandell Asset Management Corp., 40 West 57th Street, 26th Floor, New York,
New York 10019.

     (c) Castlerigg International is a private investment fund that is primarily
engaged in the business of investing in securities and other investment
opportunities. Castlerigg International invests substantially all of its assets
indirectly in Castlerigg Master Investments, a master trading vehicle that is
primarily engaged in the business of investing in securities and other
investment opportunities. Castlerigg Holdings is the controlling shareholder of
Castlerigg Master Investments and Castlerigg International is the controlling
shareholder of Castlerigg Holdings. Castlerigg Global Select is a private
investment fund that is primarily engaged in the business of investing in
securities and other investment opportunities. Castlerigg Global Select invests
substantially all of its assets indirectly in CGS, a master trading vehicle that
is primarily engaged in the business of investing in securities and other
investment opportunities. CGSH is the controlling shareholder of CGS and
Castlerigg Global Select is the controlling shareholder of CGSH. SAMC is the
discretionary investment manager of Castlerigg International, Castlerigg
Holdings, Castlerigg Master Investments, Castlerigg Global Select, CGS and CGSH.
Sandell is the controlling shareholder, Chief Executive Officer and Portfolio
Manager of SAMC. Information regarding the directors, executive officers and/or
control persons of Castlerigg Master Investments, SAMC, Castlerigg
International, Castlerigg Holdings, Castlerigg Global Select, CGS and CGSH
(collectively, the "Instruction C Persons") is set forth in Appendix III
attached hereto.

     (d) None of the Reporting Persons has, during the last five years, been
convicted in a criminal proceeding (excluding traffic violations or similar
misdemeanors).

     (e) None of the Reporting Persons has, during the last five years, been a
party to a civil proceeding of a judicial or administrative body of competent
jurisdiction




----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 11 of 13 Pages
----------------------------                        ----------------------------


and as a result of such proceeding was or is subject to a judgment, decree or
final order enjoining future violations of, or prohibiting or mandating
activities subject to, federal or state securities laws or finding any violation
with respect to such laws.

     (f) Castlerigg Master Investments, Castlerigg International and Castlerigg
Holdings are British Virgin Islands companies. SAMC, Castlerigg Global Select,
CGS and CGSH are Cayman Islands exempted companies. Sandell is a citizen of
Sweden.

ITEM 3.       SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION

     Funds for the purchase of the shares of Common Stock reported herein to be
held by Castlerigg Master Investments and CGS were derived from their respective
general working capital and margin account borrowings made in the ordinary
course of business. A total of approximately $64.50 million was paid to acquire
the shares of Common Stock reported herein.

ITEM 4.       PURPOSE OF TRANSACTION

     The Reporting Persons acquired the shares of Common Stock for investment
purposes in the ordinary course of business because they believed the shares to
be undervalued in the market.

     On March 12, 2007, SAMC sent a letter to the board of directors (the
"Board") of the Issuer (the "March 12 Letter") thanking the Board for meeting
with representatives of SAMC and expressing concern over (i) the lack of
definitive plans for return of capital to shareholders from the Issuer's
outsized cash balance and (ii) the Issuer's apparent complacency on cost
controls. In order to maximize shareholder value SAMC recommended in the March
12 Letter that the Issuer (i) commit to at least $15 million of expense
reduction by the end of 2007 and (ii) expeditiously return at least $300 million
of the current cash balance to its shareholders, in the form of a $200 million
Dutch tender offer at a premium to the current share price and a $100 million
special dividend. SAMC suggested that, if the market fails to adequately value
the Issuer or management is unable to take the steps necessary to close the
value gap, the Board should immediately engage a financial advisor to sell the
Issuer in whole or in part. SAMC further stated that it was currently
considering its options with respect to nominating an alternative slate of
directors at the Issuer's upcoming annual meeting. A copy of the March 12 Letter
is attached hereto as Exhibit A and incorporated herein by reference.

     Except as described herein, none of the Reporting Persons has any plans or
proposals which relate to, or could result in, any of the matters referred to in
paragraphs (a) through (j), inclusive, of the instructions to Item 4 of Schedule
13D. The Reporting Persons may, at any time and from time to time, review or
reconsider their position and/or change their purpose and/or formulate plans or
proposals with respect thereto. Depending on the Issuer's response to the March
12 Letter, among other things, the Reporting Persons may consider proposing a
slate of nominees for election as directors at the Issuer's next annual meeting.
Representatives of SAMC have engaged and may in the future engage in discussions
with members of the Board and management as well as with other shareholders of
the Issuer and other interested parties regarding the suggestions contained in
the March 12 Letter and other matters of interest to the Issuer's shareholders.

     Although none of the Reporting Persons has any specific plan or proposal to
acquire or dispose of the shares of Common Stock, each Reporting Person at any
time and from time to time may (i) acquire additional shares or securities of
the Issuer, (ii) dispose of any or all of its securities of the Issuer or (iii)
enter into privately negotiated derivative transactions with institutional
counterparties to hedge the market risk of some or all of its positions in the
securities of the Issuer, depending upon an ongoing evaluation of the investment
in such securities, prevailing market conditions, other investment
opportunities, liquidity requirements of the Reporting Persons, and/or other
investment considerations.




----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 12 of 13 Pages
----------------------------                        ----------------------------

ITEM 5.       INTEREST IN SECURITIES OF THE ISSUER

     (a) Each of Castlerigg Master Investments, SAMC, Castlerigg International,
Castlerigg Holdings and Sandell may be deemed to beneficially own the 1,523,443
shares of Common Stock held by Castlerigg Master Investments, representing
approximately 4.8% of the outstanding shares of Common Stock. Each of CGS, CGSH,
Castlerigg Global Select, SAMC and Sandell may be deemed to beneficially own the
1,247,761 shares of Common Stock held by CGS, representing approximately 4.0% of
the outstanding shares of Common Stock. The Reporting Persons may be deemed to
be a "group" by virtue of the matters discussed in Item 4, which "group" may be
deemed to beneficially own an aggregate of 2,771,204 shares of Common Stock,
representing approximately 8.8% of the outstanding shares of Common Stock. The
percentages used herein are based upon the 31,469,062 shares of Common Stock
reported to be outstanding as of February 16, 2007 by the Issuer in its Annual
Report on Form 10-K for the period ended December 31, 2006, filed with the
Securities and Exchange Commission on February 16, 2007.

     (b) None of the Reporting Persons has sole power to vote or direct the vote
or sole power to dispose or direct the disposition of shares of Common Stock.
Each of Castlerigg Master Investments, SAMC, Castlerigg International,
Castlerigg Holdings and Sandell has shared power to vote or direct the vote and
shared power to dispose or direct the disposition of the 1,523,443 shares of
Common Stock held by Castlerigg Master Investments. Each of CGS, CGSH,
Castlerigg Global Select, SAMC and Sandell has shared power to vote or direct
the vote and shared power to dispose or direct the disposition of the 1,247,761
shares of Common Stock held by CGS.

     (c) Information concerning transactions in the shares of Common Stock
effected by the Reporting Persons during the past sixty days is set forth in
Appendix I hereto.

     (d) No person other than Castlerigg Master Investments, SAMC, Castlerigg
International, Castlerigg Holdings and Sandell is known to have the right to
receive or the power to direct the receipt of dividends from, or the proceeds
from the sale of, the shares of Common Stock held by Castlerigg Master
Investments. No person other than CGS, CGSH, Castlerigg Global Select, SAMC and
Sandell is known to have the right to receive or the power to direct the receipt
of dividends from, or the proceeds from the sale of, the shares of Common Stock
held by CGS.

     (e) Not applicable.

ITEM 6.       CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH
              RESPECT TO SECURITIES OF THE ISSUER

     Except as otherwise set forth herein, the Reporting Persons do not have any
contract, arrangement, understanding or relationship with any person with
respect to the securities of the Issuer.

ITEM 7.       MATERIAL TO BE FILED AS EXHIBITS

     The following documents are filed as appendices and exhibits:

Appendix I:   Transactions Effected During the Past Sixty Days

Appendix II:  Joint Filing Agreement

Appendix III: Information Regarding the Instruction C Persons

Appendix IV:  Powers of Attorney


Exhibit A:    Letter to Issuer's Board of Directors dated March 12, 2007



----------------------------                        ----------------------------
CUSIP No.  45678T201            SCHEDULE 13D        Page 13 of 13 Pages
----------------------------                        ----------------------------

                                    Signature

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

     Dated: March 12, 2007

            CASTLERIGG MASTER INVESTMENTS LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            SANDELL ASSET MANAGEMENT CORP.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Chief Executive Officer


            CASTLERIGG INTERNATIONAL LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG INTERNATIONAL HOLDINGS LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG GLOBAL SELECT FUND LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CGS, LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG GS HOLDINGS, LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            /s/ Thomas E. Sandell
            ---------------------
            Thomas E. Sandell




                                   APPENDIX I
                TRANSACTIONS EFFECTED DURING THE PAST SIXTY DAYS

(All transactions were regular market transactions effected on The NASDAQ Global
Select Market)

-------------     ---------------                   -----------     -----------
Date of           Person                             Amount of       Price per
transaction       effecting                         securities        share
                  transaction                      Bought/(Sold)     or unit
-------------     ---------------                   -----------     -----------
 01/03/07         CGS                                  30,875         20.26
 01/03/07         Castlerigg Master Investments        16,625         20.26
 01/05/07         CGS                                   1,517         20.25
 01/05/07         Castlerigg Master Investments           818         20.25
 01/08/07         CGS                                  16,250         20.52
 01/08/07         Castlerigg Master Investments         8,750         20.52
 01/19/07         CGS                                     585         21.55
 01/19/07         CGS                                    (584)        21.74
 01/19/07         Castlerigg Master Investments          (316)        21.74
 01/19/07         Castlerigg Master Investments           315         21.55
 02/02/07         CGS                                 184,830         21.45
 02/02/07         CGS                                 117,000         22.15
 02/02/07         Castlerigg Master Investments        99,524         21.45
 02/02/07         Castlerigg Master Investments        63,000         22.14
 02/06/07         CGS                                  16,250         22.44
 02/06/07         Castlerigg Master Investments         8,750         22.44
 02/12/07         CGS                                  55,250         22.66
 02/12/07         Castlerigg Master Investments        29,750         22.66
 02/13/07         CGS                                  42,250         23.06
 02/13/07         Castlerigg Master Investments        22,750         23.06
 02/15/07         CGS                                  23,660         23.10
 02/15/07         CGS                                  20,280         23.03
 02/15/07         Castlerigg Master Investments        10,920         23.03
 02/15/07         Castlerigg Master Investments        12,740         23.10
 02/16/07         CGS                                  53,625         23.16
 02/16/07         Castlerigg Master Investments        28,875         23.16
 02/20/07         CGS                                  21,840         23.14
 02/20/07         Castlerigg Master Investments        11,760         23.14
 02/21/07         CGS                                  97,500         23.15
 02/21/07         Castlerigg Master Investments        52,500         23.15
 02/22/07         CGS                                  75,476         22.97
 02/22/07         Castlerigg Master Investments        40,641         22.97
 02/23/07         CGS                                   6,500         23.15
 02/23/07         Castlerigg Master Investments         3,500         23.15
 02/26/07         CGS                                  59,439         23.18
 02/26/07         Castlerigg Master Investments        32,006         23.18
 02/27/07         CGS                                 171,520         23.06
 02/27/07         Castlerigg Master Investments        92,357         23.06
 02/28/07         CGS                                   8,226         22.91
 02/28/07         Castlerigg Master Investments         4,430         22.91
 03/01/07         CGS                                 171,072         23.13
 03/01/07         Castlerigg Master Investments        92,117         23.13
 03/02/07         CGS                                 172,082         23.27
 03/02/07         Castlerigg Master Investments        92,660         23.27
 03/05/07         CGS                                  92,547         23.46
 03/05/07         Castlerigg Master Investments        49,833         23.46
 03/06/07         Castlerigg Master Investments        14,268         23.92
 03/06/07         CGS                                   7,683         23.92
 03/08/07         Castlerigg Master Investments           520         24.79
 03/08/07         Castlerigg Master Investments        20,150         24.91
 03/08/07         CGS                                  10,850         24.91
 03/08/07         CGS                                     280         24.79
 03/09/07         Castlerigg Master Investments        30,000         25.10
 03/09/07         Castlerigg Master Investments         2,500         25.19
 03/09/07         Castlerigg Master Investments         2,100         25.10
 03/09/07         CGS                                 270,000         25.10
 03/09/07         CGS                                  22,500         25.19
 03/09/07         CGS                                  18,900         25.10
 03/12/07         Castlerigg Master Investments        15,915         25.47
 03/12/07         CGS                                 143,243         25.47





                                   APPENDIX II
                             JOINT FILING AGREEMENT

The undersigned acknowledge and agree that the foregoing statement on Schedule
13D is filed on behalf of each of the undersigned and that all subsequent
amendments to this statement on Schedule 13D may be filed on behalf of each of
the undersigned without the necessity of filing additional joint filing
agreements. The undersigned acknowledge that each shall be responsible for the
timely filing of such amendments, and for the completeness and accuracy of the
information concerning him or it contained herein and therein, but shall not be
responsible for the completeness and accuracy of the information concerning the
others, except to the extent that he or it knows or has reason to believe that
such information is inaccurate.


     Dated: March 12, 2007

            CASTLERIGG MASTER INVESTMENTS LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            SANDELL ASSET MANAGEMENT CORP.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Chief Executive Officer


            CASTLERIGG INTERNATIONAL LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG INTERNATIONAL HOLDINGS LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG GLOBAL SELECT FUND LIMITED

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CGS, LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            CASTLERIGG GS HOLDINGS, LTD.

            By: /s/ Thomas E. Sandell
                ---------------------
                Thomas E. Sandell, Director


            /s/ Thomas E. Sandell
            ---------------------
            Thomas E. Sandell





                                  Appendix III
                 Information Regarding the Instruction C Persons

Castlerigg Master Investments, SAMC, Castlerigg International, Castlerigg
Holdings, CGS, CGSH and Castlerigg Global Select have no executive officers or
directors other than as follows:


Sandell serves as a director of Castlerigg Master Investments, SAMC, Castlerigg
International, Castlerigg Holdings, CGS, CGSH and Castlerigg Global Select and
as an executive officer of Castlerigg International and SAMC.

Daniel Mignon serves as a director of Castlerigg Master Investments, Castlerigg
International, Castlerigg Holdings, CGS, CGSH and Castlerigg Global Select.

InterCaribbean Services Ltd. serves as a director of Castlerigg Master
Investments, Castlerigg International and Castlerigg Holdings.

Timothy O'Brien and Richard Gashler serve as executive officers of SAMC.

Hilmi Unver serves as a director of CGS, CGSH and Castlerigg Global Select.

To the best of the Reporting Persons' knowledge, none of the Instruction C
Persons during the last five years has been convicted in a criminal proceeding
(excluding traffic violations or other similar misdemeanors) or been a party to
a civil proceeding of a judicial or administrative body of competent
jurisdiction and as a result of such proceeding was or is subject to a judgment,
decree or final order enjoining future violations of, or prohibiting or
mandating activities subject to, federal or state securities laws or finding any
violation with respect to such laws. To the best of the Reporting Persons'
knowledge, except as set forth in this statement on Schedule 13D, none of the
Instruction C Persons owns any shares of Common Stock.


                                                            
-----------------  --------------------    ----------------------    --------------------
Name               Principal               Address                   Citizenship /
                   Occupation                                        Place of Organization
-----------------  --------------------    ----------------------    --------------------
Sandell            See Item 2              See Item 2                See Item 2
-----------------  --------------------    ----------------------    --------------------
Mignon             Executive of an         Le Prince de Galles       Belgium
                   investment manager      10 Avenue de Grande-
                                           Bretagne
                                           MC-98000 Monte-Carlo
                                           MONACO
-----------------  --------------------    ----------------------    --------------------
InterCaribbean     Fund Administrator      c/o Citco BVI Limited     Curacao,
Services Ltd.                              Citco Building            Netherlands
                                           Wickhams Cay              Antilles
                                           PO Box 662
                                           Road Town, Tortola
                                           British Virgin Islands
-----------------  --------------------    ----------------------    --------------------
O'Brien            Chief Financial         40 West 57th Street,      United States
                   Officer of              26th Floor
                   SAMC                    New York, New York
                                           10019
-----------------  --------------------    ----------------------    --------------------
Gashler            General Counsel         40 West 57th Street,      United States
                   of SAMC                 26th Floor
                                           New York, New York
                                           10019
-----------------  --------------------    ----------------------    --------------------
Unver              Portfolio Manager       98 rue de Saint-Jean      Switzerland
                                           case postale 5240
                                           CH-1211 Geneve 11
                                           Switzerland


                                   Appendix IV
                               POWERS OF ATTORNEY

                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that Castlerigg Master Investments Ltd., whose
signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         CASTLERIGG MASTER INVESTMENTS LTD.

                                    By: Sandell Asset Management Corp.
                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that Sandell Asset Management Corp., whose
signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         SANDELL ASSET MANAGEMENT CORP.

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that Castlerigg International Limited, whose
signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         CASTLERIGG INTERNATIONAL LIMITED

                                    By: Sandell Asset Management Corp.


                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                              POWER OF ATTORNEY
                              -----------------

KNOW ALL MEN BY THESE PRESENTS, that Castlerigg International Holdings Limited,
whose signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         CASTLERIGG INTERNATIONAL HOLDINGS LIMITED

                                    By: Sandell Asset Management Corp.
                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that Castlerigg Global Select Fund, Limited,
whose signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         CASTLERIGG GLOBAL SELECT FUND, LIMITED

                                    By: Sandell Asset Management Corp.
                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that CGS, Ltd., whose signature appears below,
constitutes and appoints each of Timothy O'Brien, Richard A. Gashler and Jamil
French as its attorney-in-fact and agent for the undersigned solely for the
purpose of executing reports required under Sections 13(d) and 16 of the
Securities Exchange Act




of 1934, as amended, and filing the same, with exhibits and appendices thereto,
and other documents in connection therewith, with the Securities and Exchange
Commission, thereby ratifying and confirming all that each said attorney-in-fact
may do or cause to be done by virtue hereof.

     Dated:  March 12, 2007         CGS, LTD.

                                    By: Sandell Asset Management Corp.
                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                                POWER OF ATTORNEY
                                -----------------

KNOW ALL MEN BY THESE PRESENTS, that Castlerigg GS Holdings, Ltd., whose
signature appears below, constitutes and appoints each of Timothy O'Brien,
Richard A. Gashler and Jamil French as its attorney-in-fact and agent for the
undersigned solely for the purpose of executing reports required under Sections
13(d) and 16 of the Securities Exchange Act of 1934, as amended, and filing the
same, with exhibits and appendices thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, thereby ratifying and
confirming all that each said attorney-in-fact may do or cause to be done by
virtue hereof.

     Dated:  March 12, 2007         CASTLERIGG GS HOLDINGS, LTD.

                                    By: Sandell Asset Management Corp.
                                        its Investment Manager

                                        By: /s/ Thomas E. Sandell
                                            ------------------------------
                                            Thomas E. Sandell
                                            Chief Executive Officer



                              POWER OF ATTORNEY
                              -----------------

KNOW ALL MEN BY THESE PRESENTS, that Thomas E. Sandell, whose signature appears
below, constitutes and appoints each of Timothy O'Brien, Richard A. Gashler and
Jamil French as his attorney-in-fact and agent for the undersigned solely for
the purpose of executing reports required under Sections 13(d) and 16 of the
Securities Exchange Act of 1934, as amended, and filing the same, with exhibits
and appendices thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, thereby ratifying and confirming all that
each said attorney-in-fact may do or cause to be done by virtue hereof.

     Dated:  March 12, 2007
                                    /s/ Thomas E. Sandell
                                    ------------------------------
                                    Thomas E. Sandell