<PAGE>

                                                                   EXHIBIT 10.66

                                AMENDMENT NO. 2
                                      TO
                               CREDIT AGREEMENT


     This Amendment No. 2 to Credit Agreement (this "Amendment"), dated as of
September 30, 1999, is entered into by and among Micron Electronics, Inc., a
Minnesota corporation ("Borrower"), Credit Suisse First Boston and U.S. Bank
National Association , as co-agents for the Lenders (the "Co-Agents"), Lenders
named as such in the Credit Agreement, and Credit Suisse First Boston, as
administrative agent for Lenders (solely in such capacity, "Agent"). Capitalized
terms used herein but not defined herein shall have the same meaning as given to
them in the Credit Agreement (as defined below).

                                   Recitals

     Whereas, Borrower, Agent (or the person who preceded it as administrative
agent), Co-Agents and Lenders entered into a Credit Agreement dated June 10,
1998, as amended by that Amendment No. 1 to Credit Agreement dated as of
November 5, 1998 (as so amended, the "Credit Agreement") whereby a revolving
line of credit was made available to Borrower;

     Whereas, Borrower desires to make or cause to be made Investments in four
new Subsidiaries, each wholly-owned directly or indirectly by Borrower;

     Whereas, the Credit Agreement in its current state would prohibit such
Investments; and

     Whereas, the parties to the Credit Agreement wish to amend the Credit
Agreement to permit such Investments.

                                   Agreement

     Now, Therefore, in consideration of the foregoing Recitals, and intending
to be legally bound, the parties hereto agree as follows:

     SECTION 1.  Amendment to Credit Agreement.

          1.1  The definition of "Guarantors" contained in Section 1.1,
"Definitions" is hereby deleted in its entirety and replaced by the following:

          "Guarantors" means each Subsidiary of Borrower as shall execute and
          deliver a Guaranty.

          1.2  The definition of "Guaranty" contained in Section 1.1,
"Definitions" is hereby deleted in its entirety and replaced by the following:

                                       1.
<PAGE>

     "Guaranty" means a Guaranty Agreement in favor of Agent and
     Lenders substantially in the form of that certain Guaranty
     Agreement dated as of the date of Amendment No. 2 to Credit
     Agreement, including without limitation, that certain
     Guaranty Agreement dated as of November 5, 1998, and that
     certain Guaranty Agreement dated as of the date of Amendment
     No. 2 to Credit Agreement.

     1.3       The following definitions are added to Section 1.1,
"Definitions":

     "1999 Guarantors" means those persons executing that certain
     Guaranty Agreement dated as of the date of Amendment No. 2
     to Credit Agreement.

     "General Guarantors" means each Subsidiary of Borrower as
     shall execute and deliver a Guaranty, provided, however,
     that no 1999 Guarantor or business entity constituting a New
     Internet Asset is a General Guarantor.

     "New Internet Assets" means (a) Micron PC Web Services, Inc.
     and (b) any assets or business entities pertaining to the
     internet, internet-related, or services fields in which
     Borrower or a Subsidiary acquires an interest on or after
     the date of Amendment No. 2 to Credit Agreement; provided,
     however, that such a business entity shall not constitute a
     New Internet Asset unless such entity either (x) merges into
     Micron PC Web Services, Inc., or (y) becomes a Subsidiary
     and executes a Guaranty.

     1.4  Section 7.7, "Investments", is hereby amended by adding new
subsections (i), (j), (k) and (l) and re-designating existing subsections (i)
and (j) as new subsections (m) and (n) respectively. New subsections (i), (j),
(k) and (l) shall read as follows: "(i) an Investment in the form of a
contribution of some or all of the assets comprising the SpecTek Memory Products
business unit (including cash) to SpecTek, LLC, a Delaware limited liability
company, (j) Investments in NETLimited, Inc., d/b/a HostPro, a California
corporation, (k) Investments in Micron Internet Services, Inc., a Delaware
corporation, (l) Investments to, in, or with respect to, any New Internet Assets
not to exceed Seventy-Five Million Dollars ($75,000,000) in the aggregate,".

     1.5  Subsection 7.7(m) of the Credit Agreement, as created by subsection
1.4 of this Amendment, is hereby further amended by adding the word "General"
before the word "Guarantors".

     1.6  Section 7.7, "Investments", is hereby further amended by adding the
following sentence to the end of the section: "Notwithstanding anything
contained herein, no Investment otherwise permitted by this section shall be
made if a Default or Event of Default shall then exist or would immediately
result therefrom."

                                       2.
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     SECTION 2. Representations and Warranties. In order to induce Agent and
Lenders to enter into this Amendment and to amend the Credit Agreement, Borrower
represents and warrants to each Lender and Agent as follows:

          2.1  Corporate Power and Authority. Borrower has all requisite
corporate power and authority to enter into this Amendment and to carry out the
transactions contemplated by, and perform its obligations under the Credit
Agreement, as amended hereby (the "Amended Agreement").

          2.2  Authorization of Agreements. The execution and delivery of this
Amendment and the performance of the Amended Agreement have been duly authorized
by all necessary corporate action on the part of Borrower.

          2.3  Binding Obligation. This Amendment has been duly executed and
delivered by Borrower and is the binding obligation of Borrower, enforceable
against it in accordance with its terms, except as such enforceability may be
limited by bankruptcy, insolvency, reorganization, liquidation, moratorium or
other similar laws of general application and equitable principles relating to
or affecting creditors' rights.

          2.4  Absence of Default. No event has occurred and is continuing or
would result from the execution, delivery or performance of this Amendment which
constitutes a Default or Event of Default. The representations and warranties
contained in the Loan Documents are true, accurate and complete in all material
respects.

     SECTION 3.  Conditions Precedent. This Amendment shall be deemed effective
upon (i) its execution and delivery to the Agent by Borrower and Majority
Lenders, (ii) the receipt by Agent of a certificate of a Responsible Person of
Borrower, and of each 1999 Guarantor, as to the effectiveness of resolutions of
the Board of Directors of Borrower and each such Guarantor authorizing Borrower
to enter into this Amendment and each such Guarantor to execute, deliver and
perform the terms of the Guaranty respectively, (iii) receipt by Agent of a
Guaranty, duly executed and delivered by each of the 1999 Guarantors, (iv)
receipt by Agent of a Reaffirmation of Guaranty duly executed by each Guarantor
party to the Guaranty Agreement dated as of November 5, 1998, and (v) receipt by
Agent of an amendment fee in the amount of $50,000 to be paid pro rata to the
Lenders.

     SECTION 4.  Full Force and Effect; Entire Agreement. Except to the extent
expressly provided in this Amendment, the terms and conditions of the Credit
Agreement shall remain in full force and effect. This Amendment and the Loan
Documents constitute and contain the entire agreement of the parties hereto and
supersede any and all prior agreements, negotiations, correspondence,
understandings and communications between the parties, whether written or oral,
respecting the subject matter hereof. The parties hereto further agree that this
Amendment and the Loan Documents comprise the entire agreement of the parties
thereto and supersede any and all prior agreements, negotiations,
correspondence, understandings and other communications between the parties
thereto, whether written or oral respecting the extension of credit by Lenders
to Borrower.

                                       3.
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     SECTION 5. Release and Waiver. Borrower hereby acknowledges and agrees that
(a) it has no claim or cause of action against Agent or any Lender or any
parent, subsidiary or affiliate thereof, or any of Agent's or any Lenders'
officers, directors, employees, attorneys or other representatives or agents in
connection with the Credit Agreement, the loans thereunder or the transactions
contemplated therein and herein; (b) it has no offset or defense against any of
its respective obligations, indebtedness or contracts in favor of Agent or any
Lender; and (c) it recognizes that Agent and Lenders have heretofore properly
performed and satisfied in a timely manner all of its obligations to and
contracts with Borrower.

     SECTION 6. Governing Law. This Amendment shall be governed by, and shall be
construed and enforced in accordance with, the internal laws of the State of New
York, without regard to conflict of laws principles.

     SECTION 7. Counterparts. This Amendment may be signed in any number of
counterparts, and by different parties hereto in separate counterparts, with the
same effect as if the signatures to each such counterpart were upon a single
instrument. All counterparts shall be deemed an original of this Amendment.

     In Witness Whereof, the parties hereto have caused this Amendment to be
executed as of the date first written above.

Borrower            Micron Electronics, Inc.


                    By: /s/ James R. Stewart
                        --------------------------------------------------
                    Printed Name: James R. Stewart
                    Title: Senior Vice President, Chief Financial Officer


Agent               Credit Suisse First Boston

                    By: /s/ Chris T. Horgan
                        --------------------------------------------------
                    Printed Name: Chris T. Horgan
                                  ----------------------------------------
                    Title: Vice President
                           -----------------------------------------------

                    By: /s/ Todd C. Morgan
                        --------------------------------------------------
                    Printed Name: Todd C. Morgan
                                  ----------------------------------------
                    Title: Director
                           -----------------------------------------------

                                       4.
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Co-Agents                Credit Suisse First Boston

                         By: /s/ Chris T Horgan
                             ---------------------------------------------
                         Printed Name: Chris T Horgan
                                       -----------------------------------
                         Title: Vice President
                                ------------------------------------------

                         By: /s/ Todd C. Morgan
                             ---------------------------------------------
                         Printed Name: Todd C. Morgan
                                       -----------------------------------
                         Title: Director
                                ------------------------------------------


                         U.S. Bank National Association

                         By: /s/ Ross Beaton
                             ---------------------------------------------
                         Printed Name: Ross Beaton
                                       -----------------------------------
                         Title: Vice President
                                ------------------------------------------

                                       5.
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Lenders                  Credit Suisse First Boston

                         By: /s/ Chris T Horgan
                             ----------------------------------------
                         Printed Name: Chris T Horgan
                                       ------------------------------
                         Title: Vice President
                                -------------------------------------

                         By: /s/ Todd C. Morgan
                             ----------------------------------------
                         Printed Name: Todd C. Morgan
                                       ------------------------------
                         Title: Director
                                -------------------------------------

                         U.S. Bank National Association

                         By: /s/ Ross Beaton
                             ----------------------------------------
                         Printed Name: Ross Beaton
                                       -------------------------------
                         Title: Vice President
                                --------------------------------------


                         Fleet National Bank

                         By: /s/ Michael S. Barclay
                             -----------------------------------------
                         Printed Name: Michael S. Barclay
                                       -------------------------------
                         Title: Vice President
                                --------------------------------------


                         KeyBank National Association

                         By: /s/ Mary K. Young
                             -----------------------------------------
                         Printed Name: May K. Young
                                       -------------------------------
                         Title: Assistant Vice President
                                --------------------------------------


                         The Bank of Nova Scotia

                         By: /s/ M. Van Otterloo
                             -----------------------------------------
                         Printed Name: M. Van Otterloo
                                       -------------------------------
                         Title: Senior Relationship Manager
                                --------------------------------------


                         The Sumitomo Bank, Limited

                         By: /s/ Bob Granfelt
                             -----------------------------------------
                         Printed Name: Bob Granfelt
                                       -------------------------------
                         Title: Vice President and Manager
                                --------------------------------------

                                       6.
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                          ACKNOWLEDGMENT OF AMENDMENT
                                      AND
                           REAFFIRMATION OF GUARANTY

     Section 1.  Each of the undersigned hereby acknowledges and confirms that
it has reviewed and approved the terms and conditions of this Amendment.

     Section 2.  Each of the undersigned hereby consents to this Amendment and
agrees that its Guaranty of the indebtedness and other obligations of Borrower
under the Credit Agreement shall continue in full force and effect, shall be
valid and enforceable and shall not be impaired or otherwise affected by the
execution of this Amendment or any other document or instrument delivered in
connection herewith.

     Section 3.  Each of the undersigned represents and warrants that, after
giving effect to this Amendment, all representations and warranties contained in
its Guaranty are true, accurate and complete as if made on the date hereof.

                         Micron PC, Inc.

                         By: /s/ Michael S. Adkins
                             --------------------------------------
                         Name:  Michael S. Adkins
                         Title: General Manager and Senior Vice President

                         Micron Commercial Computer Systems, Inc.,
                              f/k/a Micron Commercial Systems, Inc.

                         By: /s/ Jill D. Smith
                             --------------------------------------
                         Name:  Jill D. Smith
                         Title: Director

                         Micron Government Computer Systems, Inc.,
                              f/k/a Micron Government Systems, Inc.

                         By: /s/ Harry B. Heisler
                             --------------------------------------
                         Name:  Harry B. Heisler
                         Title: General Manager and Vice President

                         Micron Computer Services, Inc.
                              f/k/a Micron Services, Inc.

                         By: /s/ Scott L. Bower
                             --------------------------------------
                         Name:  Scott L. Bower
                         Title: General Manager and Vice President

                                       7.