EXHIBIT 4.28

THIS WARRANT AND THE  SECURITIES  ISSUABLE  UPON  EXERCISE  HEREOF HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE "SECURITIES ACT") NOR UNDER ANY
STATE  SECURITIES  LAW AND MAY  NOT BE  PLEDGED,  SOLD,  ASSIGNED  OR  OTHERWISE
TRANSFERRED UNTIL (1) A REGISTRATION  STATEMENT UNDER THE SECURITIES ACT AND ANY
APPLICABLE STATE  SECURITIES LAWS HAS BECOME EFFECTIVE WITH RESPECT THERETO,  OR
(2) RECEIPT BY THE COMPANY OF AN OPINION OF COUNSEL TO THE COMPANY TO THE EFFECT
THAT  REGISTRATION  UNDER THE SECURITIES ACT OR APPLICABLE STATE SECURITIES LAWS
IS NOT REQUIRED IN CONNECTION WITH THE PROPOSED TRANSFER.

THIS  WARRANT MAY NOT BE  EXERCISED  EXCEPT IN  COMPLIANCE  WITH ALL  APPLICABLE
FEDERAL AND STATE SECURITIES LAWS TO THE REASONABLE  SATISFACTION OF THE COMPANY
AND LEGAL COUNSEL FOR THE COMPANY.


            Void after 5:00 p.m. New York City Time, on July 19, 2003

                Warrant to Purchase 80,000 Shares of Common Stock

               WARRANT TO PURCHASE COMMON STOCK, PAR VALUE $0.01,

                                       OF

                                ADATOM.COM, INC.

         This is to Certify That, FOR VALUE RECEIVED,  GABRIEL M. CERRONE or his
permitted assigns ("Holder") is entitled to purchase,  subject to the provisions
of this Warrant, from Adatom.com,  Inc., a Delaware corporation (the "Company"),
up to EIGHTY  THOUSAND  (80,000) fully paid,  validly  issued and  nonassessable
shares of Common  Stock,  par value  $.01 per  share,  of the  Company  ("Common
Stock")  at a price of $2.25 per  share at any time or from time to time  during
the period from the date hereof to July 19, 2003,  as set forth under (a) below,
but not later than 5:00 p.m. New York City Time, on July 19, 2003. The number of
shares of Common Stock to be received  upon the exercise of this Warrant and the
price to be paid for each  share of Common  Stock may be  adjusted  from time to
time as hereinafter set forth. The shares of Common Stock  deliverable upon such
exercise,  and as adjusted from time to time, are hereinafter sometimes referred
to as "Warrant  Shares"  and the  exercise  price of a share of Common  Stock in
effect at any time and as adjusted  from time to time is  hereinafter  sometimes
referred to as the "Exercise Price."

         (a)      EXERCISE OF WARRANT.  This Warrant may be exercised in  whole,
or in part in  increments  of not less than 20,000  shares,  at any time or from
time to time, until July 19, 2003. This Warrant may be exercised by presentation
and surrender hereof to the Company at its principal office, or at the office of
its stock  transfer  agent,  if any,  with the Purchase  Form annexed  hereto as
Exhibit A duly executed and accompanied by payment of the Exercise Price for the
number of Warrant  Shares  specified in such form and any and all transfer taxes
applicable to such exercise.  As soon as  practicable  after each such exercise,
but not later than 30 days from the date of such  exercise,  the  Company  shall
issue and deliver to the Holder a  certificate  or  certificate  for the Warrant
Shares issuable upon such exercise,  registered in the name of the Holder or its
designee.  If this Warrant  should be exercised in part only, the Company shall,
upon  surrender  of this  Warrant  for  cancellation,  execute and deliver a new
Warrant  evidencing  the rights of the Holder thereof to purchase the balance of
the Warrant Shares purchasable thereunder.

         (b)      RESERVATION OF SHARES.  The Company shall at all times reserve
for issuance and/or delivery upon exercise of this Warrant such number of shares
of its Common Stock as shall be required for issuance and delivery upon exercise
of the Warrant.


                                      E-19

<PAGE>


         (c)      FRACTIONAL SHARES. No fractional shares or script representing
fractional  shares  shall be issued  upon the  exercise  of this  Warrant.  With
respect to any  fraction of a share  called for upon any  exercise  hereof,  the
Company  shall  pay to the  Holder  an  amount  in cash  equal to such  fraction
multiplied by the Current Market Value of a share, determined as follows:

         (1)      If  the  Common  Stock  is  listed  on  a  national securities
         exchange or admitted to unlisted trading privileges on such exchange or
         listed for trading on the Nasdaq  National  Market,  the Current Market
         Value shall be the last reported sale price of the Common Stock on such
         exchange  or  market  on the  last  business  day  prior to the date of
         exercise  of this  Warrant or if no such sale is made on such day,  the
         average  closing bid and asked prices for such day on such  exchange or
         market; or

         (2)      If the Common Stock is not so listed or admitted  to  unlisted
         trading  privileges,  but is traded on the Nasdaq Small Cap Market, the
         Current  Market Value shall be the average of the closing bid and asked
         prices for such day on such  market  and if the Common  Stock is not so
         traded, the Current Market Value shall be the mean of the last reported
         bid and asked  prices  reported  by Pink  Sheets  LLC or the Nasdaq OTC
         Bulletin  Board  on the  last  business  day  prior  to the date of the
         exercise of this Warrant if such prices are so reported; or

         (3)      If the Common Stock is not so listed or admitted  to  unlisted
         trading  privileges  and bid and asked prices are not so reported,  the
         Current  Market  Value  shall be an  amount,  not less than book  value
         thereof as at the end of the most  recent  fiscal  year of the  Company
         ending prior to the date of the exercise of the Warrant,  determined in
         such  reasonable  manner as may be prescribed by the Board of Directors
         of the Company.

         (d)      TRANSFER, ASSIGNMENT OR LOSS OF WARRANT.

         (1)      Neither  this  Warrant,  nor the shares of Common Stock issued
         upon  the  exercise  of  all  or a  portion  of  this  Warrant,  may be
         transferred  (other than by will or pursuant to the laws of descent and
         distribution)  except with the  Company's  prior written  consent.  Any
         transfer of the Warrant,  or the shares of Common Stock issued upon the
         exercise of the Warrant,  must be done in  compliance  with  applicable
         federal and state securities laws;

         (2)      By acceptance of this Warrant, the Holder agrees to  be  bound
         by the terms of a  standard  market  standoff  agreement  requested  by
         underwriters with respect to a public offering of Common Stock acquired
         pursuant to this Warrant;

         (3)      Upon surrender of this Warrant to the Company at its principal
         office or at the office of its stock transfer  agent,  if any, with the
         Assignment  Form annexed  hereto duly executed and funds  sufficient to
         pay any transfer tax, and with the consent of the Company,  the Company
         shall, without charge, execute and deliver a new Warrant in the name of
         the assignee  named in such  instrument of assignment  and this Warrant
         shall promptly be cancelled.

         (4)      Upon receipt by the Company of evidence  satisfactory to it of
         the loss, theft, destruction or mutilation of this Warrant, and (in the
         case  of  loss,  theft  or  destruction)  of  reasonably   satisfactory
         indemnification,  and upon surrender and  cancellation of this Warrant,
         if  mutilated,  the Company  will  execute and deliver a new Warrant of
         like tenor and date. Any such new Warrant  executed and delivered shall
         constitute  an  additional  contractual  obligation  on the part of the
         Company,  whether or not this Warrant so lost,  stolen,  destroyed,  or
         mutilated shall be at any time enforceable by anyone.

         (e)      ANTI-DILUTION PROVISIONS.  The Exercise Price in effect at any
         time  and the  number  and  kind of  securities  purchasable  upon  the
         exercise of the  Warrant  shall be subject to  adjustment  from time to
         time upon the happening of certain events as follows:


                                      E-20

<PAGE>

         (1)      In case the Company shall

                  (i)      declare  a  dividend or make  a  distribution  on its
                  outstanding shares of  Common Stock in shares of Common Stock,

                  (ii)     subdivide  or  reclassify  its  outstanding shares of
                  Common Stock into a greater number of shares, or

                  (iii)    combine  or  reclassify  its  outstanding  shares  of
                  Common Stock into a smaller  number of shares,

         the number of shares  subject to the Warrant  shall be  proportionately
         increased,   and  the   Exercise   Price  of  the   Warrant   shall  be
         proportionately  decreased,  in the case of actions specified in (l)(i)
         or (ii)  above;  and the  number  of  shares  shall be  proportionately
         decreased,  and the Exercise Price  proportionately  increased,  in the
         case of actions  specified in (l)(iii) above.  Such adjustment shall be
         made successively whenever any event listed above shall occur.

         (2)      No adjustment in the Exercise  Price shall be required  unless
         such adjustment  would require an increase or decrease of at least five
         cents ($0.05) in such price;  provided,  however,  that any adjustments
         which by  reason of this  Subsection  (2) are not  required  to be made
         shall be  carried  forward  and taken into  account  in any  subsequent
         adjustment  required to be made hereunder.  All calculations under this
         Section (e) shall be made to the nearest  cent or to the nearest  whole
         share, as the case may be.

         (3)      Whenever the Exercise Price is adjusted,  as herein  provided,
         the Company shall  promptly but no later than 30 days after any request
         for such an adjustment by the Holder,  cause a notice setting forth the
         adjusted  Exercise Price and adjusted number of Warrant Shares issuable
         upon  exercise  of  each  Warrant,   and,  if  requested,   information
         describing  the  transactions  giving rise to such  adjustments,  to be
         mailed to the Holder at his last  address  appearing  in the records of
         the  Company,  and  shall  cause a copy  thereof  to be  mailed  to its
         transfer  agent,  if any. The Company may retain a firm of  independent
         certified  public  accountants  selected by the Board of Directors (who
         may be the regular  accountants  employed  by the  Company) to make any
         computation  required by this Section (e), and a certificate  signed by
         such firm  shall be  conclusive  evidence  of the  correctness  of such
         adjustment.

         (4)      In the event that at any time,  as  a result of an  adjustment
         made  pursuant  to  Subsection  (1) above,  the Holder of this  Warrant
         thereafter  shall become entitled to receive any shares of the Company,
         other than Common Stock,  thereafter the number of such other shares so
         receivable upon exercise of this Warrant shall be subject to adjustment
         from  time to time in a manner  and on terms as  nearly  equivalent  as
         practicable  to  the  provisions  with  respect  to  the  Common  Stock
         contained in Subsection (1) above.

         (5)      Irrespective of  any  adjustments in the Exercise Price or the
         number or kind of shares  purchasable  upon  exercise of this  Warrant,
         Warrants  theretofore or thereafter  issued may continue to express the
         same price and number and kind of shares as are stated in the  Warrants
         previously issued.

         (f)      REGISTRATION RIGHTS. The Company hereby grants the  Holder the
right to "piggy back" the Warrant Shares on each Registration  Statement for the
sale of Common Stock (or any  securities of a successor  company of the Company)
filed by the  Company  which  includes  shares of Common  Stock to be offered on
behalf of selling  securityholders  (provided  that there is no objection by any
such  selling  securityholder  to the  inclusion  of any  Warrant  Shares in the
Registration  Statement),  at the  Company's  cost  and  expense  (except  those
incurred by the Holder for legal fees and  commissions).  The obligations of the
Company  under this Section (f) expire upon the earlier of (i) after the Company
has  afforded the  opportunity  for the Holder to exercise  registration  rights
under this  Section  (f) for three  registrations,  (ii) when all of the Warrant
Shares held by the Holder may be sold by the Holder under Rule 144 without being
subject to any volume  restrictions,  or (iii) the third anniversary of the date
of this  Warrant.  The  Company  shall give the  Holder at least 30 days'  prior
notice of its intent to file a Registration Statement. The Company shall use its
best efforts to keep any Registration Statement onto which Holder has "piggy


                                      E-21

<PAGE>

backed" his Warrant Shares effective for a period of not less than 270 days from
the date  whereby  the  Holder is first  entitled  to sell  thereunder,  or such
shorter  period  terminating  when the Holder has sold all of his  shares.  Such
"piggy back" rights are subject to standard underwriters' approval and holdback,
whereby the Holder's rights to sell in a public offering may be limited pro rata
with the other stockholders,  and shall not apply to any Warrant Shares that can
be sold under SEC Rule 144 without  volume  restrictions.  For  purposes of this
Section  (f),  the term  Registration  Statement  shall  mean  any  registration
statement for the sale of common stock or other  securities filed by the Company
or filed by any  successor  entity  (in the  case of  merger,  reclassification,
change, consolidation,  sale or conveyance of the Company) under the Act (except
for a registration statement on Form S-4, Form S-8 or any successor form thereto
and  except  for  a  registration  statement  filed  pursuant  to  that  certain
Registration  Rights  Agreement  between the Company and the  purchasers  of the
Company's Series
A Convertible Preferred Stock, dated June 22, 2000).

         (g)      NOTICES  TO  WARRANT  HOLDERS.  So long as this  Warrant shall
be  outstanding,  (i)  if the  Company  shall  pay  any  dividend  or  make  any
distribution  upon the Common  Stock or (ii) if the  Company  shall offer to the
holders of Common  Stock for  subscription  or purchase by them any share of any
class or any other rights or (iii) if any capital reorganization of the Company,
reclassification of the capital stock of the Company, consolidation or merger of
the Company with or into another corporation,  sale, lease or transfer of all or
substantially  all  of  the  property  and  assets  of the  Company  to  another
corporation, or voluntary or involuntary dissolution,  liquidation or winding up
of the Company shall be effected, then in any such case, the Company shall cause
to be mailed by  certified  mail to the Holder,  at least 15 days prior the date
specified in (x) or (y) below,  as the case may be, a notice  containing a brief
description of the proposed action and stating the date on which (x) a record is
to be taken for the purpose of such  dividend,  distribution  or rights,  or (y)
such reclassification, reorganization, consolidation, merger, conveyance, lease,
dissolution,  liquidation or winding up is to take place and the date, if any is
to be fixed, as of which the holders of Common Stock or other  securities  shall
receive  cash  or  other  property   deliverable  upon  such   reclassification,
reorganization,  consolidation,  merger, conveyance, dissolution, liquidation or
winding up.

         (h)      COMPLIANCE  WITH  SECURITIES ACT.  The  Holder, by  acceptance
 hereof,

         (1)      represents  (i)  that  this Warrant and the Common Stock to be
         issued upon exercise of this Warrant are being  acquired for investment
         only and not with a view toward  distribution or resale,  and (ii) that
         he will not offer,  sell or  otherwise  dispose of this  Warrant or any
         Common Stock  purchasable  upon  exercise of this Warrant  except under
         circumstances  which will not result in a violation  of the  Securities
         Act; and

         (2)      agrees that upon  exercise of this  Warrant, the Holder  shall
         (i) submit to the  Company a signed  copy of  Exhibits A and C attached
         hereto,  (ii)  provide  such  additional   information  regarding  such
         holder's  financial  and  investment  background  as  the  Company  may
         reasonably  request,  and (iii) all shares of Common  Stock issued upon
         exercise of this Warrant (unless  registered  under the Securities Act)
         shall be stamped or imprinted with a restrictive  legend  substantially
         in the form of the following:

                  THESE SHARES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT
                  OF 1933 (THE "SECURITIES  ACT") NOR UNDER ANY STATE SECURITIES
                  LAWS  AND MAY NOT BE  PLEDGED,  SOLD,  ASSIGNED  OR  OTHERWISE
                  TRANSFERRED  UNTIL  (1) A  REGISTRATION  STATEMENT  UNDER  THE
                  SECURITIES ACT AND ANY APPLICABLE  STATE  SECURITIES  LAWS HAS
                  BECOME EFFECTIVE WITH RESPECT  THERETO,  OR (2) RECEIPT BY THE
                  COMPANY OF AN OPINION OF COUNSEL TO THE  COMPANY TO THE EFFECT
                  THAT REGISTRATION UNDER THE SECURITIES ACT OR APPLICABLE STATE
                  SECURITIES  LAWS  IS  NOT  REQUIRED  IN  CONNECTION  WITH  THE
                  PROPOSED TRANSFER.

         (i)      NO AVOIDANCE.   The  Company  will  not,  by amendment  of its
charter or through reorganization,  consolidation,  merger, dissolution, sale of
assets or any other voluntary  action,  avoid or seek to avoid the observance or
performance  of any of the terms of this Warrant,  but will at all times in good
faith assist in the


                                      E-22

<PAGE>

carrying  out of all such terms and in the  taking of all such  action as may be
necessary  or  appropriate  in order to protect the rights of the holder of this
Warrant against impairment.

         (j)      CERTAIN LIMITATIONS OF  HOLDER.   The  Holder,  by  acceptance
hereof, agrees that:

         (1)      STOP-TRANSFER  NOTICES.  In order to  ensure  compliance  with
         the restrictions  referred to herein, the Company may issue appropriate
         "stop transfer" instructions to its transfer agent, if any, and, if the
         Company transfers its own securities, it may make appropriate notations
         to the same effect in its own records;

         (2)      REFUSAL TO  TRANSFER.  The  Company  shall not be  required to
         (i) transfer the Warrant on its books or transfer any  securities  that
         have been sold or  otherwise  transferred  in  violation  of any of the
         provisions of this  Warrant;  or (ii) treat as the owner of the Warrant
         or any such  securities,  or accord the right to vote or pay  dividends
         to, any  purchaser or other  transferee to whom such  securities  shall
         have been so transferred; and

         (3)      RIGHTS OF STOCKHOLDERS.  No  holder  of  the  Warrant shall be
         entitled to vote or receive  dividends or be deemed a stockholder,  nor
         shall anything contained herein be construed to confer upon the Holder,
         as such, any of the rights of a stockholder of the Company or any right
         to vote for the election of  directors or upon any matter  submitted to
         stockholders at any meeting thereof,  or to give or withhold consent to
         any corporate  action (whether upon any  recapitalization,  issuance of
         stock,  reclassification  of  stock,  change  of par value or change of
         stock to no par value, consolidation, merger, conveyance, or otherwise)
         or to receive notice of meetings,  or to receive  dividends,  until the
         Warrant  shall  have been  exercised  and the Common  Stock  shall have
         become deliverable, as provided herein.

         (k)      GOVERNING LAW.  The terms and conditions of this Warrant shall
be  governed  by and  construed  in  accordance  with the  laws of the  State of
Delaware.

         (l)      MISCELLANEOUS.  The  headings in this Warrant are for purposes
of convenience  and reference only, and shall not be deemed to constitute a part
hereof.  Neither  this  Warrant  nor any term  hereof  may be  changed,  waived,
discharged or terminated in any manner except by an instrument in writing signed
by the Company and the Holder.

         All notices and other  communications from the Company to the holder of
this Warrant  shall be mailed by  first-class  registered  or certified  mail or
recognized  commercial courier service,  postage or delivery charges prepaid, to
the  address  furnished  to the  Company in  writing by the last  holder of this
Warrant who shall have furnished an address to the Company in writing.

         IN WITNESS  WHEREOF,  the Company  has caused this  Warrant to Purchase
Common Stock to be duly executed by one of its duly authorized officers.

                                                     ADATOM.COM, INC.


                                            By:      ___________________________
                                                     Richard S. Barton
                                                     Chairman of the Board
                                                     and Chief Executive Officer

                                            Date:    July 19, 2000



                                      E-23

<PAGE>

                                    Exhibit A

                                  PURCHASE FORM

                          Dated ____________, 20_______



1. The undersigned  hereby  irrevocably elects to exercise the within Warrant to
the extent of purchasing _______ shares of Common Stock and hereby makes payment
of _____________ in payment of the actual exercise price thereof,  together with
all applicable transfer taxes, if any.

2. Please issue a certificate or certificates representing said shares of Common
Stock in the  name of the  undersigned  or in such  other  name as is  specified
below:

                  (Please typewrite or print in block letters)


                        ---------------------------------
                                     (Name)

                        ---------------------------------

                        ---------------------------------
                                    (Address)

3.       The  undersigned  has  reviewed, signed  and  enclosed   an  Investment
Representation Statement in the form attached as Exhibit C to the Warrant.


                           ---------------------------------
                           Signature of Warrantholder



                                      E-24

<PAGE>

                                    Exhibit B

                                 ASSIGNMENT FORM


         FOR VALUE RECEIVED, ______________ hereby sells, assigns and  transfers
unto

Name _______________________________________
(Please typewrite or print in block letters)

Address ____________________________________

the right to purchase Common Stock  represented by this Warrant to the extent of
______ shares as to which such right is exercisable and does hereby  irrevocably
constitute  and appoint  ___________  as  attorney,  to transfer the same on the
books of the Company with full power of substitution in the premises.


Date ____________, 20_______


Signature _____________________________




                                      E-25

<PAGE>


                                    Exhibit C

                                ADATOM.COM, INC.

                                     WARRANT

                       INVESTMENT REPRESENTATION STATEMENT


AMOUNT:  ________________________

DATE:    _______________, 2000


         In connection  with the purchase of the  above-listed  securities  (the
"Securities") from ADATOM.COM, INC. ("the Company"), I the undersigned Purchaser
represent to the Company the following:

         (a)      I am  aware of the Company's business  affairs  and  financial
condition,  and have acquired sufficient  information about the Company to reach
an  informed  and  knowledgeable  decision  to  acquire  the  Securities.  I  am
purchasing these Securities for my own account for investment  purposes only and
not with a view to, or for the resale in  connection  with,  any  "distribution"
thereof for  purposes of the  Securities  Act of 1933,  as amended  ("Securities
Act").

         (b)      I  understand  that  the  Securities  have not been registered
under the Securities Act in reliance upon a specific exemption therefrom,  which
exemption  depends  upon,  among  other  things,  the  bona  fide  nature  of my
investment intent as expressed herein.

         (c)      I  further  understand  that  the  Securities  must  be   held
indefinitely unless  subsequently  registered under the Securities Act or unless
an exemption from registration is otherwise  available.  Moreover,  I understand
that the Company is under no obligation to register the Securities. In addition,
I understand  that the  certificate  evidencing the Securities will be imprinted
with a legend which  prohibits  the transfer of the  Securities  unless they are
registered  or such  registration  is not required in the opinion of counsel for
the Company.

         (d)      I am aware of the  provisions of Rule 144,  promulgated  under
the  Securities  Act,  which,  in substance,  permits  limited  public resale of
"restricted  securities"  acquired,  directly  or  indirectly,  from the  issuer
thereof (or from an affiliate of such  issuer),  in a  transaction  or series of
transactions not involving a non-public offering, subject to the satisfaction of
certain conditions.

         (e)      I  further  understand  that  at  the  time I wish to sell the
Securities there may be no public market upon which to make such a sale.

         (f)      I further understand that in the event all of the requirements
of Rule 144 are not satisfied, registration under the Securities Act, compliance
with Regulation A, or some other  registration  exemption will be required;  and
that,  notwithstanding the fact that Rule 144 is not exclusive, the Staff of the
SEC has expressed its opinion that persons  proposing to sell private  placement
securities  other than in a registered  offering and otherwise  than pursuant to
Rule 144 will  have a  substantial  burden  of  proof  in  establishing  that an
exemption from registration is available for such offers or sales, and that such
persons and their respective  brokers who participate in such transactions do so
at their own risk.


                                -----------------------------------
                                          Name of Purchaser

                                -----------------------------------
                                          Date


                                      E-26