Document:

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                                                                    EXHIBIT 4.39

                             [Form of Certificate]

                                  WAM!NET INC.

                             A Minnesota Corporation

No. __                                               ______ Shares of Class F
                                                     Convertible Preferred Stock

     This certifies that ______________________ is the registered holder of
_________ Shares of Class F Convertible Preferred Stock, par value $0.01 per
share (see reverse side), transferable only on the books of the Corporation by
the holder hereof in person or by Attorney upon surrender of this Certificate
properly endorsed.

     IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its duly authorized officers this ___ day of February, 2000.

                                       -----------------------------------------
                                       Gary L. Hokkanen, President

                                       -----------------------------------------
                                       Edward J. Driscoll, Jr., Secretary
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     The Class F Convertible Preferred Stock has the rights and preferences as
set forth in the Certificate of Designation of Class F Preferred Stock as filed
of record with the Minnesota Secretary of State on February 3, 2000.

     The securities evidenced hereby are subject to the terms of that certain
stockholders agreement, dated as of March 4, 1999 as amended on March 14, 2000;
by and among the Company, Silicon Graphics, Inc., MCI Worldcom, Inc., Winstar
Communications, Inc., Winstar Credit Corp. and Cerberus Partners, L.P. A copy of
the Stockholder's Agreement has been filed with the Secretary of the Corporation
and is available upon request. The securities evidenced hereby have not been
registered under the Securities Act of 1933, as amended (the "Act") and may not
be resold, transferred or otherwise disposed of other than in a transaction
exempt from, or not subject to, the registration requirements of the Act or
pursuant to an effective registration statement thereunder.

     For value received, ______________________________ does hereby sell, assign
and transfer unto _____________________________________________________ Shares
represented by the within Certificate and does hereby irrevocably constitute and
appoint ___________________________________ Attorney to transfer the said Shares
on the books of the within named Corporation with full power of substitution in
the premises.

Dated: ______________________

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

Note: The signature on this assignment must correspond with the name as written
upon the face of the Certificate, in every particular, without alteration or
enlargement or any change whatever.

                                      -2-<PAGE>

                                                                    EXHIBIT 4.40
                             [Form of Certificate]

                                  WAM!NET INC.

                             A Minnesota Corporation

No. __                                                   _____ Shares of Class G
                                                     Convertible Preferred Stock

     This certifies that _____________ is the registered holder of Shares of
Class G Convertible Preferred Stock, par value $0.01 per share (see reverse
side), transferable only on the books of the Corporation by the holder hereof in
person or by Attorney upon surrender of this Certificate properly endorsed.

     IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its duly authorized officers this _____ day of March, 2000.

                                       -----------------------------------------
                                       Gary L. Hokkanen, President

                                       -----------------------------------------
                                       Edward J. Driscoll, Jr., Secretary
<PAGE>

     The Class G Convertible Preferred Stock has the rights and preferences as
set forth in the Certificate of Designation of Class G Preferred Stock as filed
of record with the Minnesota Secretary of State on March 6, 2000.

     The securities evidenced hereby are subject to the terms of that certain
Stockholders Agreement, dated as of February 18, 2000, by and among the
Corporation and Buyers listed on Schedule 1.1, including certain restrictions on
transfer. A copy of this Agreement has been filed with the Secretary of the
Corporation and is available upon request. The securities evidenced hereby have
not been registered under the Securities Act of 1933, as amended (the "Act") and
may not be resold, transferred or otherwise disposed of other than in a
transaction exempt from, or not subject to, the registration requirements of the
Act or pursuant to an effective registration statement thereunder.

     For value received, _____________________________________ does hereby sell,
assign and transfer unto __________________________________________ Shares
represented by the within Certificate and does hereby irrevocably constitute and
appoint ___________________________________ Attorney to transfer the said Shares
on the books of the within named Corporation with full power of substitution in
the premises.

Dated:  _____________________

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

Note: The signature on this assignment must correspond with the name as written
upon the face of the Certificate, in every particular, without alteration or
enlargement or any change whatever.

                                       2.<PAGE>

                                                                    EXHIBIT 4.41

                    EXERCISABLE ON OR BEFORE, AND VOID AFTER
                    5:00 P.M. MINNEAPOLIS TIME APRIL 30, 2004

                        Certificate for 200,000 Warrants

                      WARRANTS TO PURCHASE COMMON STOCK OF

                                  WAM!NET Inc.

              INCORPORATED UNDER THE LAWS OF THE STATE OF MINNESOTA

     THIS CERTIFIES that MCI WORLDCOM, Inc., ("Holder") or assigns, is the owner
of the number of Warrants set forth above, each of which represents the right to
purchase from WAM!NET Inc., Minnesota corporation (the "Company"), at any time
after April 30, 1999 and on or before 5:00 Minneapolis time, April 30, 2004,
upon compliance with and subject to the conditions set forth herein, one share
(subject to adjustments referred to below) of the Common Stock of the Company,
par value $.01 per share (such shares or other securities or property
purchasable upon exercise of the Warrants being herein called the "Shares").

     Upon any exercise of less than all the Warrants evidenced by this Warrant
Certificate, there shall be issued to the Holder a new Warrant Certificate in
respect of the Warrants as to which this Warrant Certificate was not exercised.

     This Warrant is subject to the following provisions, terms and conditions:

     1. Exercise; Transferability. The rights represented by this Warrant may be
exercised by the Holder hereof, in whole or in part (but not as to a fractional
share of Common Stock), by written notice of exercise delivered to the Company
ten (10) days prior to the intended date of exercise and by the surrender of
this Warrant (properly endorsed if required) at the principal office of the
Company and by paying in full, as provided herein, the purchase price of $.01
per share (the "Exercise Price").

     Payment upon exercise of the rights represented by this Warrant may be made
at the option of the Holder (a) in cash or by certified or official bank check
payable to the order of the Company, (b) by surrendering to the Company for
cancellation and retirement any number shares of 1999 Class A Preferred Shares,
<PAGE>

par value $10.00 per share, which shares shall each be valued for purposes
hereof at their par value of $10.00 plus the sum of any then accumulated and
unpaid dividends thereon, (c) by cancellation and discharge of the Company from
all or any portion of any debt in the amount then owed by the Company to the
Holder on a dollar for dollar basis, including principal whether or not then due
and payable together with any interest accrued and unpaid thereon, or (d) by any
combination of any or all of the foregoing.

     This Warrant may not be transferred or divided into two or more Warrants of
smaller denominations, nor may any Common Stock issued pursuant to exercise of
this Warrant be transferred unless this Warrant or shares have been registered
under the Securities Act of 1933, as amended ("Securities Act") and applicable
state laws, or unless the Holder of the certificate obtains an opinion of
counsel satisfactory to the Company and its counsel that the proposed transfer
may be effected without registration pursuant to exemptions under the Securities
Act and applicable state laws.

     2. Issuance of Shares. The Company agrees that the shares purchased hereby
shall be deemed to be issued to the record Holder hereof as of the close of
business on the date on which this Warrant shall have been surrendered and the
payment made for such shares as aforesaid. Subject to the provisions of the next
succeeding paragraph, certificates for the shares of stock so purchased shall be
delivered to the Holder hereof within a reasonable time, not exceeding ten (10)
days after the rights represented by this Warrant shall have been so exercised,
and, unless this Warrant has expired, a new Warrant representing the number of
shares, if any, with respect to which this Warrant shall not then have been
exercised shall also be delivered to the Holder hereof within such time.

     Notwithstanding the foregoing, however, the Company shall not be required
to deliver any certificate for shares of stock upon exercise of this Warrant,
except in accordance with the provisions, and subject to the limitations, of
paragraph 7 hereof.

     3. Covenants of Company. The Company covenants and agrees that all shares
which may be issued upon the exercise of the rights represented by this Warrant
will, upon issuance, be duly authorized and issued, fully paid, nonassessable
and free from all taxes, liens and charges with respect to the issue thereof,
and without limiting the generality of the foregoing, the Company covenants and
agrees that it will from time to time take all such action as may be required to
assure that the par value per share of the Common Stock is at all times equal to
or less than the then effective purchase price per share of the Common Stock
issuable pursuant to this Warrant. The Company further covenants and agrees that
during the period within which the rights represented by this Warrant may be
exercised, the Company will at all times have authorized, and reserved for the
purpose of issue

                                      -2-
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or transfer upon exercise of the subscription rights evidenced by this Warrant,
a sufficient number of shares of its Common Stock to provide for the exercise of
the rights represented by this Warrant.

     4. Adjustments. The above provisions are, however, subject to the following
provisions:

          (a) No fractional shares of Common Stock are to be issued upon the
     exercise of the Warrant, but the Company shall pay a cash adjustment in
     respect of any fraction of a share which would otherwise be issuable in an
     amount equal to the same fraction of the market price per share of Common
     Stock on the date of exercise as determined in good faith by the Company.

          (b) If any capital reorganization or reclassification of the capital
     stock of the Company, or consolidation or merger of the Company with
     another corporation, or the sale of all or substantially all of its assets
     to another corporation shall be effected in such a way that holders of
     Common Stock shall be entitled to receive stock, securities or assets with
     respect to or in exchange for Common Stock then, as a condition of such
     reorganization, reclassification, consolidation, merger or sale, lawful and
     adequate provision shall be made whereby the Holder hereof shall hereafter
     have the right to purchase and receive upon the basis and upon the terms
     and conditions specified in this Warrant and in lieu of the shares of the
     Common Stock of the Company immediately theretofore purchasable and
     receivable upon the exercise of the rights represented hereby, such shares
     of stock, securities or assets as may be issued and payable with respect to
     or in exchange for a number of outstanding shares of such Common Stock
     equal to the number of shares of such stock immediately theretofore
     purchasable and receivable upon the exercise of the rights represented
     hereby had such reorganization, reclassification, consolidation, merger or
     sale not taken place, and in any such case appropriate provisions shall be
     made with respect to the rights and interests of the Holder of this Warrant
     to the end that the provisions hereof (including without limitation
     provisions for adjustments of the Warrant purchase price and of the number
     of shares purchasable upon the exercise of this Warrant) shall thereafter
     be applicable, as nearly as may be, in relation to any shares of stock,
     securities or assets thereafter deliverable upon the exercise hereof. The
     Company shall not effect any such consolidation, merger or sale, unless
     prior to the consummation thereof the successor corporation (if other than
     the Company) resulting from such consolidation, merger, or the corporation
     purchasing such assets shall assume by written instrument executed and
     mailed to the registered Holder hereof at the last address of such holder
     appearing on the books of the Company, the obligation to deliver to such
     holder such shares of stock, securities or assets as, in accordance with
     the foregoing provisions, such holder may be entitled to purchase.

                                      -3-
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          (c) If the Company shall at any time or from time to time (i)
     distribute (otherwise than as a dividend in cash or in Common Stock or
     securities convertible into or exchangeable for Common Stock) to the
     holders of Common Stock any property or other securities, or (ii) declare a
     dividend upon the Common Stock (to the extent payable otherwise than out of
     earnings or earned surplus, as indicated by the accounting treatment of
     such dividend in the books of the Company, and otherwise than in Common
     Stock or securities convertible into or exchangeable for Common Stock), the
     Company shall reserve and the Holder of this Warrant shall thereafter upon
     exercise hereof be entitled to receive, with respect to each share of
     Common Stock purchased hereunder, without any change in, or payment in
     addition to, the exercise price, the amount of any property or other
     securities which would have been distributable to such holder had such
     holder been a holder of one share of Common Stock on the record date of
     such distribution or dividend (or if no record date was established by the
     Company, the date such distribution or dividend was paid).

     5. Common Stock. As used herein, the term "Common Stock" means the
Company's presently authorized shares of Common Stock and shall also include any
capital stock of any class of the Company hereafter authorized which shall not
be limited to fixed sum or percentage in respect of the rights of the holders
thereof to participate in dividends or in the distribution of assets upon the
voluntary or involuntary liquidation, dissolution or winding up of the Company.

     6. No Voting Rights. This Warrant shall not entitle the Holder hereof to
any voting rights or other rights as a stockholder of the Company.

     7. Notice of Transfer of Warrant or Resale of Shares. The Holder of this
Warrant, by acceptance hereof, agrees to give written notice to the Company
before transferring this Warrant, or transferring any Common Stock issued upon
the exercise hereof, of such holder's intention to do so, describing briefly the
manner of any proposed transfer. Promptly upon receiving such written notice the
Company shall present copies thereof to the Company counsel and if in the
opinion of such counsel the proposed transfer complies with federal and state
securities laws and may be effected without registration or qualification (under
any Federal or State law), the Company, as promptly as practicable, shall notify
such holder of such opinion, whereupon such holder shall be entitled to transfer
this Warrant or to dispose of shares of Common Stock received upon the previous
exercise of this Warrant, provided that an appropriate legend may be endorsed on
this Warrant or the certificates for such shares respecting restrictions upon
transfer thereof necessary or advisable in the opinion of counsel to the Company
to prevent further transfers which would be in violation of Section 5 of the
Securities Act of 1933.

                                      -4-
<PAGE>

     If in the opinion of Company's counsel referred to in this paragraph 7
hereof, the proposed transfer or disposition of shares described in the written
notice given pursuant to this paragraph 7 may not be effected without
registration or qualification of this Warrant or the shares of Common Stock
issued on the exercise hereof, the Company shall promptly give written notice
thereof to the Holder hereof, and the Holder will limit its activities in
respect to such as, in the opinion of such counsel, are permitted by law.

     8. Registration Rights. If the Company, at any time after the later of
three (3) years from the date hereof until two (2) years after the complete
exercise of this Warrant, but in no event later than April 30, 2004, proposes to
claim an exemption under Section 3(b) for a public offering of any of its
securities or to register under the Securities Act of 1933 (except by a Form S-8
or other inappropriate Form for registration) any of its securities, it will
give written notice to all registered holders of Warrants, and all registered
holders of shares of Common Stock acquired upon the exercise of Warrants, of its
intention to do so and, on the written request of any registered holders given
within twenty (20) days after receipt of any such notice (which request shall
specify the Warrants or shares of Common Stock intended to be sold or disposed
of by such registered holder and describe the nature of any proposed sale or
other disposition thereof), the Company will use its best efforts to cause all
such Warrants and/or shares, the registered holders of which shall have
requested the registration or qualification thereof, to be included in such
notification or registration statement proposed to be filed by the Company;
provided, however, that no such inclusion shall be required (i) if the Shares
may then be sold by the holder thereof without limitation under Rule 144(k), or
comparable successor rule of the Securities and Exchange Commission, or (ii) if
the managing underwriter of such offering reasonably determines that including
such Shares would unreasonably interfere with such offering. The Company will
pay all expenses of registration. The Warrant holders shall pay all commissions
or discounts applicable to the sale of the included Shares, together with any
expenses of counsel retained by them in connection with their sale of the
Shares.

                                      -5-
<PAGE>

     IN WITNESS WHEREOF, WAM!NET, Inc. has caused this Warrant to be signed by
its duly authorized officer and this Warrant to be dated _______ __, 1999.

                                       WAM!NET Inc.

                                       By:      /s/ Edward J. Driscoll
                                              -----------------------------
                                              Name:  Edward J. Driscoll
                                              Title: Chief Executive Officer

                                      -6-

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