<PAGE>   1
                                                                  EXHIBIT 10.1


                       FIRST AMENDMENT TO PURCHASE AND SALE AGREEMENT


         THIS FIRST AMENDMENT TO PURCHASE AND SALE AGREEMENT (the "First
Amendment") is made and entered into as of the _____ day of September, 1996, by
and among Software Spectrum, Inc., a Texas corporation ("SSI"), Software
Spectrum (NZ) Limited, duly incorporated under the laws of New Zealand
("Hybrid") (SSI and Hybrid are, jointly and severally, referred to herein as
"Buyer"), Essentially Group Limited, duly incorporated under the laws of New
Zealand (the "Company"), Essentially Group (NZ) Limited, duly incorporated
under the laws of New Zealand and a wholly-owned subsidiary of the Company
("NZ"), Essentially Software (Wellington) Limited, duly incorporated under the
laws of New Zealand and a wholly-owned subsidiary of NZ ("Wgtn"), McNabb No. 2
Family Trust dated November 1, 1990, McNabb No. 3 Family Trust dated November
1, 1990, The McNabb Family Trust dated July 1, 1986  (collectively, the "McNabb
Family Trusts"), RMAD Trust dated May 23, 1993 ("RMAD"), David Colvin,
individually ("Colvin"), Gary McNabb, individually ("McNabb") (the Company, NZ
and Wgtn are sometimes referred to herein individually as a "Seller" and
collectively as the "Sellers") (the Company, NZ, Wgtn, the McNabb Family
Trusts, RMAD, Colvin and McNabb are sometimes referred to herein collectively
as the "Selling Group") and Gary McNabb as Sellers' Representative.  This First
Amendment amends that certain Purchase and Sale Agreement (the "Purchase
Agreement") dated April 2, 1996 by and among the parties hereto.

                                R E C I T A L S

         WHEREAS, pursuant to the Purchase Agreement, Buyer acquired the
Australia Shares and Assets and assumed certain liabilities of Sellers;

         WHEREAS, certain issues have arisen with respect to (i) the
finalization of the Audit required by the Purchase Agreement, and (ii) the
determination of the Total Consideration payable under the Purchase Agreement;

         WHEREAS, the parties desire to fully resolve all claims of any party
under the Purchase Agreement relating to these matters; and

         WHEREAS, Robert Parkinson has resigned as Sellers' Representative and
Gary McNabb has been appointed to serve as Sellers' Representative by each
member of the Selling Group;

         NOW, THEREFORE, in consideration of the recitals and the mutual
covenants and agreements contained herein, and other good and valuable
consideration, the receipt of which is hereby acknowledged, the parties do
hereby agree as follows:

         1.      Defined Terms.  All capitalized terms used herein and not
otherwise defined in this First Amendment shall have the respective meanings
set forth in the Purchase Agreement.

         2.      Determination of Total Consideration; Obligations.  (a) Buyer
and Sellers have determined that the Total Consideration to be paid by Buyer
for the Australia Shares and
<PAGE>   2
the Assets pursuant to Article II of the Purchase Agreement shall be equal to
$9.2 million (NZ).  Buyer and Sellers' Representative, promptly following the
execution of this First Amendment, will instruct the Escrow Agent:  (i) to
return to Buyer (a) all of the Purchase Shares held pursuant to the Escrow
Agreement, and (b) $3.5 million (NZ) of the Cash Portion together with any and
all interest earned on the escrowed funds; and (ii) to disburse $500,000 (NZ)
to Selling Group, less any amount necessary to satisfy the Sellers' obligations
under Section 2(b) hereof, in such manner as is directed by the Sellers'
Representative.

                 (b)      Except as expressly set forth herein, Sellers hereby
confirm that Sellers are solely responsible for any and all expenses, costs and
other charges relating to the Audit (including all amounts owed to Coopers &
Lybrand) and to the engagement of Brown Woolley Graham.  Sellers shall provide
Buyer, at or prior to any disbursement to Sellers from the Escrowed Amount, of
evidence satisfactory to Buyer of payment of such fees; provided, however,
Buyer agrees that it will reimburse Sellers for the following:

                     (i)  an amount equal to $5,000 (NZ) payable by Sellers to
         Brown Woolley Graham for fees relating to work performed by Brown
         Woolley Graham at Buyer's request subsequent to Closing;

                    (ii)  50% of the fees incurred by Sellers, not to exceed in
         the aggregate $30,000 (NZ), that exceed the amount accrued on the
         Sellers' financial statements attached as Exhibit "A" hereto for the
         fiscal year ended March 31, 1996 relating to any services performed by
         Coopers & Lybrand, Brown Woolley Graham and Cort & Co. in connection
         with the preparation of the Audit required under the Purchase
         Agreement.

                 (c)      Sellers acknowledge that pursuant to the Asset
Agreement, any and all receivables of any type or character of the Company, NZ
and Wgtn, including all federal tax refunds, if any, have been assigned to the
Buyer as of the Closing Date, and Sellers acknowledge that they have no right
or interest therein.

         3.      Audit.  Sellers acknowledge that Sellers to date have been
unable to deliver to Buyer the Audit required to be delivered pursuant to
Section 2.1 of the Purchase Agreement.  Buyer waives any breach or violation of
the Purchase Agreement arising out of the Sellers' failure to deliver the
Audit, however, Sellers and each member of the Selling Group hereby covenants
to Buyer that the final draft of the financial statements of Sellers for the
year ended March 31, 1996 attached hereto as Exhibit "A" will be approved and
adopted by each of the boards of directors of the Sellers at a duly called and
convened meeting of each of the Sellers on or before disbursement of the Escrow
Fund by the Escrow Agent.  The Sellers and the Selling Group represent and
warrant to Buyer that the financial statements of Sellers for the year ended
March 31, 1996 delivered to Buyer prior to the date hereof attached hereto as
Exhibit "A" are true, complete and correct in all respects and have been
prepared in accordance with GAAP and there are no liabilities relating to the
business previously conducted by the Sellers (whether accrued, contingent or
otherwise) that are not set forth in such financial statements.  Sellers will
use their commercially reasonable best efforts to have the Audit completed and
delivered to Buyer promptly following the date hereof.  Notwithstanding the
foregoing, in no event shall the disbursement from the Escrow



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<PAGE>   3
occur until Sellers deliver to Buyer audited financial statements of Australia
and its subsidiaries.

         4.      Sale of Purchase Shares.  SSI directly or through one of its
subsidiaries agrees to repurchase an aggregate of 25,000 of the Purchase Shares
from the members of the Selling Group in the following amounts at a price set
forth below:

<TABLE>
<CAPTION>
                                     Number of                Purchase Price              Total Purchase
            Name                       Shares                    Per Share                     Price  
          --------                  -----------               --------------                ----------
 <S>                                  <C>                       <C>                        <C>
 Gary McNabb                          20,000                    $29.70(NZ)                 $594,000(NZ)


 David Colvin                          5,000                    $29.70(NZ)                 $148,500(NZ)


 Total                                25,000                    $29.70(NZ)                 $742,500(NZ)
</TABLE>

In consideration of the foregoing, Buyer and the Selling Group hereby
acknowledge and agree that, except as set forth below, SSI shall have no
obligation to register under the United States Securities Act of 1933, as
amended, the Purchase Shares delivered to the Selling Group at Closing, and
Section 5.7 of the Purchase Agreement is hereby deleted from the Purchase
Agreement provided that subsections 5.7(f) and (h) shall remain in full force
and effect.  Each member of the Selling Group reaffirms its representations and
agreements with respect to the acquisition of such Purchase Shares as set forth
in the Purchase Agreement.

         5.      McNabb Employment Agreement; Non-competition.  SSI and McNabb
have determined that McNabb's Employment Agreement with Software Spectrum (NZ)
Limited dated April 2, 1996 shall be terminated effective as of September 30,
1996.  McNabb, SSI and SSI (NZ) hereby agree that the non-competition
provisions set forth in Section 3.5(a)(i) and (ii) of the McNabb Employment
Agreement shall be limited to 18 months and that with respect to McNabb only,
the provisions of Section 5.2(a) of the Purchase Agreement shall be modified
and amended such that any time period set forth in Section 5.2(a) with greater
than 18 months remaining thereon shall in no event be deemed to exceed 18
months from the Closing Date.  McNabb hereby acknowledges that Buyer, and each
of Buyer's affiliates has no further obligation to McNabb for any severance,
termination, vacation, leave, bonus or any other payment of any type or
character whatsoever arising out of McNabb's Employment Agreement or his
employment arrangement with SSI (NZ), other than the payment of McNabb's base
salary and a pro rata share of any bonuses actually earned by McNabb pursuant
to the McNabb Employment Agreement through September 30, 1996.

         6.      Release of Buyer.  In consideration of the foregoing
agreements concerning the determination of the final Total Consideration, each
of the Sellers and the Selling Group, their representatives, trustees,
successors and assigns does hereby release and forever discharge Buyer, their
agents, officers, directors, employees, representatives and all persons natural
or corporate in privity with them or any of them from any and all claims or
causes





                                      -3-
<PAGE>   4
of action of any kind whatsoever, arising under contract, at common law,
statutory or otherwise, which any of them has or might have, known or unknown,
now existing or that might arise hereafter, directly or indirectly attributable
to the Purchase Agreement or any transaction set forth in or contemplated by
the Purchase Agreement of any kind or character whatsoever.  The purpose of the
foregoing release is to relinquish and surrender all claims of any type or
character for payment or compensation of any kind, past, present or future,
which any Seller or member of the Selling Group might have against those hereby
released, whether known or unknown, arising under or pursuant to the Purchase
Agreement.

         7.      Release of Sellers and Selling Group.  In consideration of the
foregoing agreement concerning the determination of the final Total
Consideration, Buyer and its successors and assigns does hereby release and
forever discharge Sellers and each member of the Selling Group, their agents,
trustees and employees and all persons natural or corporate in privity with
them or any of them from any and all claims or causes of action of any kind
whatsoever, arising under contract, at common law, statutory or otherwise,
which either Buyer has or might have, known or unknown, now existing or that
might arise hereafter, directly or indirectly attributable to method of
determination of the Total Consideration as set forth in Article II of the
Purchase Agreement and the failure to deliver the Audit pursuant to the
Purchase Agreement, provided the foregoing shall not relieve or release the
Sellers or the Selling Group from any of their representations, warranties or
other obligations under the Purchase Agreement or otherwise.

         8.      RELEASE OF MCNABB FROM GUARANTEES.  BUYER AGREES TO INDEMNIFY
AND HOLD MCNABB HARMLESS FROM ANY AND ALL LIABILITY ARISING FROM ANY
OUTSTANDING PERSONAL GUARANTY EXECUTED BY MCNABB IN FAVOR OF EITHER TRADE
SUPPLIERS OR LESSORS OF REAL PROPERTY FOR WHICH BUYER HAS ASSUMED THE
OBLIGATIONS THEREFOR UNDER THE PURCHASE AGREEMENT AND WHICH WERE SIGNED BY
MCNABB ON OR PRIOR TO THE CLOSING DATE.

         9.      Status of Purchase Agreement.  Except as expressly modified
hereby, the Purchase Agreement and all obligations, liabilities, covenants,
representations and warranties of each of the parties thereto shall remain in
full force and effect and shall not be affected, modified or limited hereby.

         10.     Counterparts.  This First Amendment may be executed in
counterparts, each of which shall be an original, but such counterparts
together shall constitute one and the same instrument.

         11.     Governing Law.  This Amendment shall be construed in
accordance with the internal laws of New Zealand.





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<PAGE>   5
         IN WITNESS WHEREOF, the parties have executed and delivered this
Agreement as of the date first above written.


IN THE PRESENCE OF:                      ESSENTIALLY GROUP LIMITED
                                        
                                        
/s/ LEANNE BIRT                          By:    /s/ GARY McNABB
---------------------------------           ----------------------------------
PA                                       Name:      Gary McNabb
33 College Hill,                               -------------------------------
Ponsonby                                 Title:     Director
                                               -------------------------------
                                        
                                        
/s/ C. O'CONNER                          BY:    /S/ ROBERT PARKINSON
---------------------------------           ----------------------------------
Secretary                                Name:      Robert Parkinson            
198 Federal St.,                               -------------------------------
Auckland                                 Title:     Director                    
                                               -------------------------------
                                        
                                        
                                         ESSENTIALLY GROUP (NZ) LIMITED
                                        
                                        
/s/ LEANNE BIRT                          By:    /s/ GARY McNABB               
---------------------------------           ----------------------------------
PA 
33 College Hill,                         Name:      Gary McNabb             
Ponsonby                                       -------------------------------
                                         Title:     Director                    
                                               -------------------------------
                                        
                                        
/s/ C. O'CONNER                          By:    /s/ ROBERT PARKINSON           
---------------------------------           ----------------------------------
Secretary                                Name:      Robert Parkinson           
198 Federal St.,                               -------------------------------
Auckland                                 Title:     Director                   
                                               -------------------------------
                                        
                                        
                                         ESSENTIALLY SOFTWARE (WELLINGTON)
                                         LIMITED
                                        
                                        
/s/ LEANNE BIRT                          By:    /s/ GARY McNABB                
---------------------------------           ----------------------------------
PA                                       Name:      Gary McNabb                
33 College Hill,                               -------------------------------
Ponsonby                                 Title:     Director                  
                                               -------------------------------
                                        
                                        
/s/ C. O'CONNER                          By:    /s/ ROBERT PARKINSON           
---------------------------------           ----------------------------------
Secretary                                Name:      Robert Parkinson         
198 Federal St.,                               -------------------------------
Auckland                                 Title:     Director                    
                                               -------------------------------


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<PAGE>   6
IN THE PRESENCE OF:                      THE MCNABB FAMILY TRUST
                                         
                                         
/s/ C. O'CONNER                         By: /s/ ROBERT PARKINSON
---------------------------------           ----------------------------------
Secretary                                       Robert Parkinson, Trustee
198 Federal St.,
Auckland                                         
                                         
/s/ LEANNE BIRT                         By: /s/ GARY JOHN McNABB
---------------------------------           ----------------------------------
PA                                              Gary John McNabb, Trustee
33 College Hill, 
Ponsonby                                         
                                         
                                         MCNABB NO. 2 FAMILY TRUST
                                         
                                         
/s/ LEANNE BIRT                          By: /s/ ANNA LOUISE McNABB
---------------------------------           ----------------------------------
PA                                               Anna Louise McNabb, Trustee
33 College Hill, 
Ponsonby                                       
                                         
/s/ C. O'CONNER                          By: /s/ ROBERT PARKINSON
---------------------------------           ----------------------------------
Secretary                                        Robert Parkinson, Trustee
198 Federal St., 
Auckland                                         
                                         
/s/ LEANNE BIRT                          By: /s/ GARY JOHN McNABB
---------------------------------           ----------------------------------
PA                                               Gary John McNabb, Trustee
33 College Hill, 
Ponsonby                                       
                                         
                                         MCNABB NO. 3 FAMILY TRUST
                                         
                                         
/s/ LEANNE BIRT                          By: /s/ ANNA LOUISE McNABB
---------------------------------           ----------------------------------
PA                                               Anna Louise McNabb, Trustee
33 College Hill, 
Ponsonby                                       
                                         
/s/ LEANNE BIRT                          By: /s/ GARY JOHN McNABB
---------------------------------           ----------------------------------
PA                                               Gary John McNabb, Trustee
33 College Hill, 
Ponsonby                                       
                                         
/s/ C. O'CONNER                          By: /s/ ROBERT PARKINSON
---------------------------------           ----------------------------------
Secretary                                        Robert Parkinson, Trustee
198 Federal St., 
Auckland


                                      -6-
<PAGE>   7
IN THE PRESENCE OF:                     RMAD TRUST
                                         
                                         
/s/ LEANNE BIRT                         By: /s/ GARY JOHN McNABB
---------------------------------           ----------------------------------
PA                                              Gary John McNabb, Trustee
33 College Hill, 
Ponsonby
                        
                                         
/s/ C. O'CONNER                         By: /s/ ROBERT PARKINSON 
---------------------------------           ---------------------------------
Secretary                                       Robert Parkinson, Trustee
198 Federal Street,
Ackland                                         
                                         

/s/ LEANNE BIRT                         /s/ DAVID COLVIN
--------------------------------        -------------------------------------
PA                                          David Colvin, Individually 
33 College Hill, 
Ponsonby                 
                                         
                                         
/s/ LEANNE BIRT                         /s/ GARY JOHN McNABB
---------------------------------       -------------------------------------
PA                                          Gary John McNabb, Individually
33 College Hill, 
Ponsonby                
                                         
                                         
/s/ LEANNE BIRT                         /s/ GARY McNABB
---------------------------------       ---------------------------------------
PA                                          Gary McNabb, 
33 College Hill,                            as Seller's Representative  
Ponsonby                 
                                         
                                         
                                        SOFTWARE SPECTRUM, INC.
                                         
                                         
/s/ LEANNE BIRT                         By: /s/ RICHARD SIMS 
---------------------------------           ----------------------------------
PA                                      Name:   Richard Sims                  
33 College Hill,                                ------------------------------
Ponsonby                                Title:  Senior Vice President
                                                ------------------------------

                                         
                                        SOFTWARE SPECTRUM (NZ) LIMITED
                                         
                                         
/s/ LEANNE BIRT                         By: /s/ RICHARD SIMS
---------------------------------          ----------------------------------
PA                                      Name:   Richard Sims
33 College Hill,                                -----------------------------
Ponsonby                                Title:
                                                -----------------------------
                                         
                                         
/s/ LEANNE BIRT                         By: /s/ DAVID COLVIN
---------------------------------           ----------------------------------
PA                                      Name:   David Colvin
33 College Hill,                                ------------------------------ 
Ponsonby                                Title:  Director
                                                ------------------------------




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