<PAGE>

                                                                    EXHIBIT 10.1
                                                                    ------------


                                 April 18, 2000


Mr. Matthew Saltzman
2 Forest Hills Drive
Avon, CT  06001

Dear Mr. Saltzman:

     This letter agreement ("Agreement") sets forth the terms of your agreement
with The Ashton Technology Group, Inc. ("Ashton") regarding your employment with
Electronic Market Center, Inc. ("EMC" or the "Company"), a majority-owned
subsidiary of Ashton.

1.   Position/Responsibilities.  You will be employed as President and Chief
     -------------------------
Operating Officer ("COO") of the Company.  Your responsibilities are set forth
on Exhibit A attached hereto.

2.   EMC.  EMC will be primarily engaged in the business of developing business
     ---
to business transactional systems to facilitate its offering of wrap fee
investment products to financial service customers.  EMC will also offer trust
services to investment clients as a platform for its wrap fee product offerings.
You as President and COO of the Company will use your best efforts to cause the
Company to fulfill the foregoing objectives.

3.   Term.  The term of your employment hereunder (the "Term") will commence on
     ----
April 18, 2000 and shall continue until April 18, 2003 unless terminated earlier
by you or by the Company as provided below.  Your employment may be renewed for
a successive three-year term upon written notice provided to you by Ashton no
later than ninety (90) days before the expiration of the Term.  In the event
that your employment is not renewed upon expiration of this Agreement, you shall
have the right to sell to Ashton, and Ashton shall have the obligation to
purchase from you, all EMC common stock then owned by you at the greater of book
value or "Share Value" (as defined in Section 4.3 of the Stockholders Agreement
of Electronic Market Center, Inc., dated April 18, 2000) per share, to be
determined independently by an independent auditor or investment banking
professional selected by the Board of Directors of the Company (the "EMC Put").

4.   Base Salary and Benefits.  You shall be paid a salary of $225,000 per year.
     ------------------------
You will be entitled to the standard benefits as in effect from time to time for
Ashton executives commensurate with your position, a current schedule of which
benefits is attached hereto as Exhibit B. You will be entitled to twenty days of
vacation annually in addition to official Company holidays.
<PAGE>

Matthew Saltzman
April 18, 2000
Page 2 of 9


5.   EMC Board of Directors.  The board of directors of EMC (the "EMC Board")
     ----------------------
shall consist of six members,  Fredric W. Rittereiser, non-executive Chairman,
K. Ivan F. Gothner, Arthur J. Bacci, one other person appointed by Ashton, you,
and one person appointed by you.  Your  position on the Board shall cease
automatically at such point you are no longer a stockholder of EMC.

6.   Funding of EMC Operations.  Ashton will be responsible for providing, or
     -------------------------
arranging the financing required to develop and launch EMC, up to $3,000,000
(such amount, the "Commitment").  Ashton will provide or arrange the Commitment
between the date hereof and July 2000.  Ashton shall advance $500,000 of this
funding to EMC at the closing of the Stock Exchange and Acquisition Agreement,
provided that such capital contribution is not applied to satisfy accrued
liabilities of E-Trustco in excess of $50,000 (exclusive of the Brightware
software vendor contract).

7.   Expense Reimbursements.  The Company will reimburse you for all reasonable
     ----------------------
business expenses you incur in fulfilling your responsibilities hereunder upon
submission of adequate documentation for such expenses and subject to Ashton
policies.

8.   Termination/Severance Pay.  Either you or Ashton shall have the right to
     -------------------------
terminate your employment at any time with or without cause by giving written
notice to that effect. The termination of employment shall be effective on the
prospective date specified in such notice (the "Effective Termination Date").

     (i) If Ashton terminates your employment without cause or if you terminate
your employment for "good reason," subject to the last sentence of this
paragraph, EMC will pay you as severance pay for a period beginning on the
Effective Termination Date and ending on April 18, 2003 (the "Severance Period")
your then current monthly salary (the "Salary").  In addition, any unexercised
stock options that you possess shall vest as of the Effective Termination Date.
The Salary will be paid on EMC's normal payroll cycle during the Severance
Period, provided, that if you become employed elsewhere during the Severance
Period the amounts otherwise payable to you under this Section 8(i) shall be
reduced by the total amount of any compensation you receive from such employment
during the Severance Period.

     For purposes of the severance pay offset provisions of this Section, the
terms "employed" and "employment" shall mean the providing of any services for
compensation whether as a full-time or part-time employee or as a consultant or
otherwise. In consideration of the severance pay herein provided you agree to
deliver to EMC on or promptly following the Effective Termination Date a
Separation and Release in the form used by EMC at that time, subject to your
agreement of the terms and conditions set forth therein, provided, that in the
event you do not deliver the Separation and Release in the form then used by EMC
your right to receive the severance pay herein provided shall terminate.  In the
event of any inconsistency regarding the terms and conditions of the Separation
and Release and this Agreement, the terms of this
<PAGE>

Matthew Saltzman
April 18, 2000
Page 3 of 9

Agreement shall govern. For purposes of this Agreement, "good reason" shall mean
Ashton's failure to perform in a timely manner its material obligations under
this Agreement or your demotion or any significant diminution of your powers and
responsibilities by the Board of EMC without cause, and shall not mean your
removal from your then current position with EMC with your express written
consent or in connection with any termination of your employment by Ashton or
EMC as the result of your disability or "for cause."

     (ii)   Ashton shall have the right to terminate your employment for cause
by giving you written notice to that effect. In the event Ashton determines that
it has reason to terminate you for cause, it shall provide you with written
notice specifying the basis underlying its determination. You shall have sixty
(60) days from the date of the written notice in which to cure any deficiencies
in your performance specified in the written notice provided by Ashton. If,
after the sixty (60) day cure period has expired, a sufficient basis still
exists for your termination, Ashton shall terminate you for cause. "Cause" means
(1) your failure to perform in a timely manner your material obligations and
responsibilities under this Agreement; (2) commission by you of a willful act of
dishonesty in the course of your duties with EMC; (3) engagement by you in
negligence or conduct injurious to Ashton, EMC or their affiliates; (4) your
failure to comply with a written instruction from the EMC Board within your
mandate as set forth herein; (5) your conviction of a crime of moral turpitude
or of a felony; or (6) your chronic alcoholism or drug abuse. If you are
terminated for cause, EMC will pay your unpaid Salary through the Effective
Termination Date.

     (iii)  If Ashton terminates your employment for cause (i) you shall not
have the right to exercise the EMC Put, and (ii) the provisions of Section 14
hereunder shall apply.  If Ashton terminates your employment without cause, or
if you terminate your employment for "good reason," then (i) you shall have the
right to exercise the EMC Put, and (ii) the provisions of Section 14 hereunder
shall not apply.

9.   Death.  If you die during your employment hereunder, this Agreement shall
     -----
terminate upon the date of your death. Thereafter, EMC shall pay to the personal
representative of your estate your unpaid Salary through the date of death. Your
estate shall also receive the benefit of any options and warrants that are
vested at the time of your death.

10.  Options.  You are hereby granted the following stock options:
     -------

     .    options to purchase 100,000 shares of common stock of Ashton at an
     exercise price per share of $4.00;

     . options to purchase 150,000 shares of common stock of Universal Trading
     Technologies Corporation ("UTTC"), a subsidiary of Ashton, at an exercise
     price of $3.50 per share;

<PAGE>

Matthew Saltzman
April 18, 2000
Page 4 of 9

     .    options to purchase 40,000 shares of common stock of Gomez Advisors,
     Inc. ("Gomez"), an affiliated company of Ashton, at an exercise price of
     $5.10 per share, from Ashton;

     .    options to purchase 1.25 million shares of common stock of EMC
     at an exercise price of $.50 per share .

     .    options to purchase 25,000 shares of common stock of Gomez, at an
     exercise price of $5.10 per share (the "Contingent Gomez Options").

     The above-described options on the common stock of Ashton and UTTC shall
vest in accordance with the following schedule:

     20%    1st anniversary of employment with EMC
     20%    2nd anniversary of employment with EMC
     60%    3rd anniversary of employment with EMC

     The options to purchase Gomez common stock will vest on the first
anniversary of your employment with EMC. The options to purchase EMC common
stock will vest upon the earlier to occur of your third anniversary of
employment with EMC or upon an initial public offering of the common stock of
EMC or any of its subsidiaries. The Contingent Gomez Options will vest at such
time that you consummate, on behalf of E-Trustco.com, Inc., a strategic
transaction with either E*Trade, Hewlett-Packard, or Citigroup. All options
granted to you will be adjusted to reflect any recapitalizations, stock splits,
mergers, etc., as provided in the respective stock option agreements. All
options granted to you will vest automatically upon a change in control in the
entity granting the stock options, as per the respective stock option
agreements.

11.  Exclusivity.  In return for the compensation payments set forth in this
     -----------
agreement, you agree to devote substantially all of your professional time and
energies to EMC, eTrustCo and the Manhattan Trust Company.

12.  Confidentiality.  In the course of your performance of your duties at EMC,
     ---------------
each of Ashton and EMC will divulge to you certain of its respective proprietary
information, including, but not limited to, information and data relating to or
concerned with its business, finances and other affairs.  You agree that you
will not divulge such proprietary information to anyone at any time whether or
not you are in the employ of Ashton and/or EMC, except as may otherwise be
required in connection with the business and affairs of Ashton or EMC, as the
case may be.  You agree to use your reasonable efforts to prevent such
disclosure by others.  Proprietary information does not include information that
is generally available to the public through no fault of yours, was already
known to you on a non-confidential basis prior to disclosure, or is subsequently
disclosed to you on a non-confidential basis by a third party not having a
confidential relationship with Ashton or EMC.
<PAGE>

Matthew Saltzman
April 18, 2000
Page 5 of 9

13.  Assignment of Rights.    You agree that any inventions, developments,
     --------------------
discoveries, improvements, processes, methods, compositions, concepts, ideas or
inventions (whether or not patentable, or copyrightable or constituting trade
secrets or proprietary information) conceived, made, created, developed or
reduced to practice by you, alone or with others, during the Term and applicable
to the type of businesses engaged in by or any prospective activity of Ashton
and EMC during such period (collectively, the "Intellectual Property") shall be
the sole and exclusive property of EMC.  By your signature below you hereby
assign all of your right, title and interest in the Intellectual Property to EMC
and agree to execute and deliver all documents requested by EMC (including,
without limitation, applications for domestic or foreign patents, copyrights, or
other proprietary rights) to protect the respective rights of EMC thereto.  All
copyrightable works that you create during the Term shall be deemed "works made
for hire".

14.  Non-competition.  You further agree that during your employment with EMC
     ---------------
and for six months after the termination of such employment for any reason, you
will not at any time engage in or participate as an officer, employee, director,
agent, consultant, representative, stockholder, investor or partner, or have any
financial interest, in any business which "competes" with Ashton or any of its
subsidiaries or successors.  For the purposes hereof, a "competing" business
shall mean any business which directly competes with any of the businesses of
Ashton as such businesses shall exist during your employment with EMC, for
example, the development and commercialization of business-to-business wrap fee
investment products or systems for facilitating transactions in the financial
markets of the type engaged in or contemplated by Ashton or EMC at the time of
termination of your employment. Ownership by you of publicly traded stock of any
corporation conducting any "competing" business shall not be deemed a violation
of this Section 14 provided you do not own more than one percent (1%) of the
stock of any such corporation.

     Additionally, for a period of six months after the termination of your
employment hereunder you will not, directly or indirectly:  (a) solicit or
entice away from the Company or Ashton (i) the employment or other services of
any executive employee of Ashton or EMC or (ii) the business of either (A) any
customer of EMC to whom you rendered services during the six month period prior
to your termination of employment (a "Specific Customer"), or (B) any person or
entity whose business you solicited by multiple personal contacts during the six
month period prior to your termination (a "Specific Contact"), or (b)
participate in any activity for any Specific Customer or Specific Contact which
is the same as or substantially similar to those activities which you performed
for such Specific Customer or proposed to perform for such Specific Contact,
unless to do so would not have a material adverse effect on the business
conducted between EMC and such Specific Customer or Specific Contact.
<PAGE>

Matthew Saltzman
April 18, 2000
Page 6 of 9

     Further, for a period of six months after the termination of your
employment hereunder you will not, directly or indirectly, hire any executive
employee of Ashton or EMC.

16.  Arbitration.  Disputes arising under or in any respect in connection with
     -----------
this Agreement, including in respect of the execution, delivery or performance
hereof (but excluding disputes as to the compliance by the arbitrators under the
provisions of this Section applicable to them), shall be arbitrated in New York
City in accordance with the Commercial Arbitration Rules of the American
Arbitration Association by three arbitrators, one selected by each party hereto
and the third selected by the two so selected (or, in the absence of agreement,
the third arbitrator shall be selected by the President of the Association of
the Bar of The City of New York at the time sitting), and with all decisions of
the arbitrators requiring the affirmative vote of at least two of the
arbitrators. Any judgment on any award rendered by the arbitrators in accordance
with such rules may be entered in any court of competent jurisdiction. The
parties intend to confer on the arbitrators the authority to resolve disputes
between the parties in respect of this Agreement and agree that no decision by
the arbitrators shall have the effect of amending this Agreement in any respect.
The costs of any such arbitration, including expenses (and legal fees) of the
other party thereto, shall be borne by the party which is the losing party in
the arbitration or, if the arbitrators' decision is unclear in that regard, as
the arbitrators shall determine in accordance with the purpose of this provision
to achieve the rules that arbitrations be commenced hereunder in circumstances
of actual disputes and not frivolously or for harassment purposes. The parties
hereto agree that any proceedings pursuant to this Section 16 shall be kept
strictly confidential and shall not be disclosed to any third party except
pursuant to court order.

17.  Miscellaneous.  Together with the attached exhibits, this letter agreement
     -------------
constitutes the entire understanding of the parties with respect to the subject
matter hereof and supersedes all prior agreements and understandings, written or
oral, among the parties with respect to such subject manner. This Agreement is
governed by the substantive laws of the State of New York. This Agreement may be
amended only in writing signed by both parties hereto. This Agreement shall
inure to the benefit of Ashton and any successor of Ashton by reorganization,
merger, consolidation or liquidation, or any assignee or transferee of all or
substantially all of the business or assets of Ashton or of any division or line
of business of Ashton with which you are at any time associated. No provision of
this Agreement shall be for the benefit of or enforceable by any third party.
Nothing in this Agreement, expressed or implied, is intended to or shall be
construed to confer upon or to give any persons or party other than the parties
hereto any rights, remedies or claims under or by reason of this Agreement.

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<PAGE>

Matthew Saltzman
April 18, 2000
Page 7 of 9

     Duplicate originals of this agreement are being provided.  Please sign
below to evidence your agreement to the foregoing, and return one original for
our records.

                                        Sincerely,

                                        THE ASHTON TECHNOLOGY GROUP, INC.



                                        By: ________________________________
                                               Arthur J. Bacci
                                               President


                                        ELECTRONIC MARKET CENTER, INC.



                                        By: ________________________________
                                               Fredric W. Rittereiser
                                               Chairman


                                        UNIVERSAL TRADING TECHNOLOGIES
                                                CORPORATION



                                        By: ________________________________
                                               Marc Gresack
                                               President


ACCEPTED AND AGREED



________________________
Matthew Saltzman

________________________
Date
<PAGE>

                                   EXHIBIT A

                   RESPONSIBILITIES OF THE PRESIDENT AND COO
                         ______________________________

          All of the following responsibilities are subject to the direction and
approval of EMC's board of directors.

     .    Supervise EMC employees, agents, representatives, etc., including,
subject to authority of EMC's board of directors, authority over hiring and
firing.

     .    Exercise authority over day-to-day operations of EMC, including
supervision of day-to-day operating expenses and expense reimbursements in
accordance with Ashton's standard policies.

     .    Prepare business plans ("Business Plans") for EMC, including budgets
and forecasts of revenue and income, and amendments thereto, which Business
Plans shall be submitted to the EMC board of directors for approval.

     .    Be responsible and accountable for the implementation and execution of
the Business Plans.

     .    Report to the EMC and Ashton boards of directors on the business and
financial condition, and significant aspects of the business operations, of EMC.

          Notwithstanding the foregoing, the President of EMC shall not be
authorized or otherwise vested with the power to do or cause to be done any of
the following without the express written consent of a majority of the EMC board
of directors:

     .    Create any subsidiaries of EMC.

     .    Incur indebtedness of EMC (other than ordinary trade payables),
including without limitation obligations for money borrowed or evidenced by
notes or other instruments, obligations under leases required to be accounted
for as capital leases under generally accepted accounting principles, the amount
available to be drawn under letters of credit under which EMC is the account
party, and guarantees of any of the foregoing.

     .    Make loans to or guarantee the obligations of any third party.

     .    Enter into or amend any contract, agreement, commitment, arrangement
or transaction (i) in which EMC purports to bind any affiliate of EMC without
the express written consent of the party to be bound or (ii) not provided for in
the business plan approved by the EMC board of directors.
<PAGE>

                                   EXHIBIT B

                PERQUISITES AND BENEFITS PROVIDED TO EXECUTIVES
                         ______________________________


          You will be eligible for the following perquisites and benefits as an
executive of EMC:

     .    EMC's bonus compensation plan;

     .    EMC's deferred compensation plan;

     .    EMC's incentive stock option programs;

     .    Key man life insurance;

     .    Medical and Dental insurance;

     .    401(k) Program