EXHIBIT 10.1 AMENDMENT NUMBER ONE TO EMPLOYMENT AGREEMENT NICHOLS RESEARCH CORPORATION

                                                                    EXHIBIT 10.1


                  AMENDMENT NUMBER ONE TO EMPLOYMENT AGREEMENT



                          XXXXXXX RESEARCH CORPORATION

                                       AND

                                XXXXXXX X. LEADER




                              Dated: March 1, 1999




                  AMENDMENT NUMBER ONE TO EMPLOYMENT AGREEMENT


         THIS  AMENDMENT  NUMBER ONE TO EMPLOYMENT  AGREEMENT  dated October 26,
1998 (the "Employment Agreement"), is entered into on this the 1st day of March,
1999,  by XXXXXXX  RESEARCH  CORPORATION  (the  Company")  and XXXXXXX X. LEADER
("Employee"). Unless otherwise defined, capitalized terms used herein shall have
the meaning ascribed to such terms in the Employment Agreement.

                              W I T N E S S E T H:

         WHEREAS,  Xxxxxxx TXEN  Corporation,  a wholly-owned  subsidiary of the
Company,  filed a Form  S-1  Registration  Statement  with  the  Securities  and
Exchange  Commission  on January 22, 1999, to register  2,500,000  shares of its
$.01 par value common stock in an initial public stock offering (the "IPO"); and

         WHEREAS,  the  Employment  Agreement  provides that  Employee  would be
issued a stock  option to purchase  shares of Xxxxxxx  TXEN  Corporation  common
stock  pursuant to the Xxxxxxx  TXEN  Corporation  1998 Stock  Option Plan which
option would be converted to a stock option to purchase  shares of the Company's
common stock if the IPO was not completed  within four months of the date of the
Employment Agreement (the "Conversion Period"); and

         WHEREAS, it is not anticipated that the IPO  will  be  completed within
the Conversion Period; and

         WHEREAS,  the Company and the Employee  desire to revise the Employment
Agreement to extend the Conversion Period.

         NOW,  THEREFORE,  in  consideration  of  the  mutual  covenants  herein
contained,  the undersigned parties do hereby amend the Employment  Agreement as
follows:

                  1.  The  sixth  sentence  of  Section  4(c) of the  Employment
         Agreement is hereby revised to delete the phrase "within four months of
         the date of this  Agreement"  and to substitute in its place the phrase
         "before  September 1, 1999." Except as amended  above,  the  Employment
         Agreement shall remain in full force and effect according to its
terms and conditions.


                                      -1-


         IN WITNESS WHEREOF,  the parties have hereunto  executed this Amendment
Number One to Employment Agreement on the date and year first above written.


                                   XXXXXXX RESEARCH CORPORATION


                                    By:Xxxxxxx X. Xxxx
                                       ----------------------------------------
                                       Xxxxxxx X. Xxxx, Chief Executive Officer


                                                     
                                       Xxxxxxx X. Leader, Employee
                                       -----------------------------------------
                                       Xxxxxxx X. Leader, Employee