<PAGE>

                                                                   Exhibit 10.28

                 AMENDMENT TO AGREEMENT FOR WHOLESALE FINANCING

      This Amendment to Agreement for Wholesale Financing is made to that
certain Agreement for Wholesale Financing entered into by and between PC
Connection, Inc., a Delaware corporation ("Dealer") and Deutsche Financial
Services Corporation (DFS) on March 25. 1998. as amended ("Agreement").

      FOR VALUE RECEIVED, Dealer and DFS agree to amend the Agreement as
follows:

      1. Dealer and DFS agree to amend paragraph 3 of the Agreement to provide
as follows:

      "3.   To secure payment of all of Dealer's current and future debts to
            DFS, whether under this Agreement or any current or future guaranty
            or other agreement, Dealer grants DFS a security interest in all
            Dealer's:

            (a) inventory and equipment, manufactured or sold by or bearing any
            trademark or trade name of Compaq Computer Corporation, Acer America
            Corporation, Apple Computer, Inc., Digital Equipment Corporation,
            Hewlett-Packard Company, Hitachi Sales Corporation of America, Power
            Computing, Texas Instruments Incorporated, Toshiba America
            Information Systems, Inc., NEC Technologies, Inc., Old America, Inc.
            (Okidata division), Canon U.S.A., Inc., Packard Bell Electronics,
            Inc., Epson America, Inc., Xerox Corporation, Tektronix, Inc., and
            Toshiba America Information Systems, Inc. or any of their
            subsidiaries or affiliated companies, whether now owned or hereafter
            acquired, and all attachments, accessories, accessions, returns,
            repossessions, exchanges, substitutions and replacements thereto,
            and all proceeds thereof; and

            (b) rebates, discounts, credits and incentive payments, now or
            hereafter due Dealer, relating to any of the above described
            inventory and equipment, and all proceeds thereof.

            All such assets are collectively referred to herein as the
            'Collateral'. All of such terms for which meanings are provided in
            the Uniform Commercial Code are used herein with such meanings. All
            Collateral financed by DFS, and all proceeds thereof, will be held
            in trust by Dealer for DFS, with such proceeds being payable in
            accordance with this Agreement."

      2. DFS and Dealer agree that the following paragraph is incorporated into
the Agreement as if fully and originally set forth therein;

      "7.1 Financial Covenants. Dealer will


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            (a) At all times maintain a Consolidated Net Worth of not less than
            the amounts specified below at the end of each of Dealer's fiscal
            quarters as indicated:

                                         Required Net Worth
            Fiscal Quarter(s)Ending on    Quarter-end Date
            --------------------------    ----------------
            06/30/99                       $   60,000,000
            09/30/99                       $   60,000,000
            12/31/99                       $   76,000,000
            03/31/00                       $   76,000,000
            06/30/00                       $   76,000,000
            09/30/00                       $   76,000,000
            12/31/00                       $   96,000,000
            03/31/01                       $   96,000,000
            06/30/01                       $   96,000,000
            09/30/01                       $   96,000,000
            12/31/01 and each fiscal
            quarter thereafter             $  120,000.000

            (b) As of each date indicated below, for the twelve months ending on
            that date, Dealer shall maintain the Consolidated Net Income
            indicated:

            Fiscal Quarter(s)Ending     Required Net Income for Previous
                                        Four Quarters on Quarter-end Date
                                        ---------------------------------
            06/30/99                       $  12,000,000
            09/30/99                       $  12,000,000
            12/31/99                       $  16,000,000
            03/31/00                       $  16,000,000
            06/30/00                       5  16,000,000
            09/30/00                       $  16,000,000
            12/31/00                       S  20,000,000
            03/31/01                       5  20.000,000
            06/30/01                       $  20,000,000
            09/30/01                       $  20,000,000
            12/31/01 and each fiscal
            quarter thereafter             $  24,000,000

            For purposes of this paragraph: (i) 'Consolidated Net Worth' means,
            at any date as of which the amount thereof shall be determined, the
            consolidated total assets of the Dealer and its affiliates, less the
            consolidated total liabilities of the Dealer and its affiliates; and
            (ii ) (ii) 'Consolidated Net Income' means the net income (or
            deficit) from operations of the Dealer and its affiliates, after
            taxes. The foregoing terms shall be determined in accordance with
            generally accepted accounting principles consistently applied"

      All other terms as they appear in the Agreement to the extent consistent
with the foregoing, are ratified and remain unchanged and in full force and
effect.


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<PAGE>

      IN WITNESS WHEREOF, Dealer and DFS have executed this Amendment to
Agreement for Wholesale Financing this 5th day of November, 1999.


                                    PC CONNECTION, INC.,

ATTEST:                             By: /s/ Jack L. Ferguson
                                       ------------------------------
----------------------              Title: Treasurer
(Assistant) Secretary                     ---------------------------


                                    DEUTSCHE FINANCIAL SERVICES CORPORATION

                                    By:
                                       ------------------------------
                                    Title:
                                          ---------------------------


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<PAGE>

      IN WITNESS WHEREOF, Dealer and DFS have executed this Amendment to
Agreement for Wholesale Financing this 5th day of November, 1999.


                                    PC CONNECTION, INC.,

ATTEST:                             By: /s/ Jack L. Ferguson
/s/ [ILLEGIBLE]                        ------------------------------
----------------------              Title: Treasurer
(Assistant) Secretary                     ---------------------------


                                    DEUTSCHE FINANCIAL SERVICES CORPORATION

                                    By:
                                       ------------------------------
                                    Title:
                                          ---------------------------
<PAGE>

                       [LETTERHEAD OF PC CONNECTION INC.]

November 15, 1999


Mr. Christopher M. Renzi
Business Development Manager
Deutsche Financial Services Corporation
100 River Ridge Drive, Suite 202
Norwood, MA 02062

Dear Chris:

I enclose the following:

1.    Copy of Amendment to Agreement for Wholesale Financing with my original
      signature.
2.    Fax copy of Steve Markiewicz's attest signature (he is in a different
      locations, and he faxed the last page with his signature).
3.    Copy of Agreement with Steve Markiewicz's original signature thereon.

I was out of the office all last week due to the death of my mother and was
unable to send this out earlier.

Yours truly,

/s/ Jack

Jack L. Ferguson.
Treasurer, Director of Finance


JLF:eg
Enclosures


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