Document:

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                                                                    EXHIBIT 4.15

                               drkoop.com, Inc.
                            7000 N. Mopac, Suite 400
                              Austin, Texas 78739

                                August 22, 2000

Infoseek Corporation
1399 Moffett Park Drive
Sunnyvale, CA

     Re   Distribution Agreement executed on April 9, 1999, as amended, by and
          between Infoseek Corporation (and certain affiliates) and drkoop.com
          and Distribution Agreement executed on April 9, 1999, as amended by
          drkoop.com and the Buena Vista Internet Group (collectively the
          "Agreements")

Ladies and Gentlemen:

          Pursuant to the Agreements, drkoop.com, Inc. (the "Company") owes you
("GO.com", as defined below) the sum of $1,033,334.00 (the "Payable").  The
purpose of this letter agreement is to confirm our agreement concerning the
Company's payment of the Payable.  The Company hereby agrees to pay to GO.com
within two (2) days of the closing of the proposed preferred stock financing
(the "Deadline") described in the Confidential Private Placement Memorandum
dated July 12, 2000 and the related cumulative supplement dated August 16, 2000
(the "Permanent Financing"), the sum of $361,666.90 (the "Cash Payment").  In
addition, the Company agrees to pay GO.com the balance of such Payable
($671,667.10) plus 6% interest thereon ($40,300.00) for a total of $711,967.10
(the "Balance") in full on or before September 1, 2001 (the "Final Payment
Date").  As used herein, "GO.com" shall mean Infoseek Corporation,
ABCNEWS/Starwave Partners, ESPN/Starwave Partners and Buena Vista Internet
Group.

          Subject to GO.com's receipt of the Cash Payment by the Deadline and
GO.com's receipt of the Balance by the Final Payment Date, and provided the
Company fulfills its registration obligations as set forth in this letter
agreement, GO.com shall release and forever discharge the Company and its
subsidiaries, affiliates, directors, officers, employees, stockholders, agents
and representatives, and each of their successors and assigns (the "Releasees")
from, and covenant not to sue or proceed against the Releasees on account of or
with respect to the Payable.

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          In consideration of the above, the Company agrees to file a
registration statement with the Securities and Exchange Commission, and under
all applicable state securities laws and statutes, of all securities of the
Company held by GO.com (including securities issuable based on warrants in the
Company's stock held by GO.com) by September 30, 2000 and to use its reasonable
best efforts to have such registration statement be declared effective as soon
as possible.

          This letter agreement shall terminate and be of no further force or
effect in the event that the Permanent Financing has not closed and the Company
has not delivered the Cash Payment to GO.com by September 1, 2000.  In addition,
this letter agreement shall terminate and be of no further force and effect in
the event the Cash Payment is not delivered to GO.com by the Deadline.

          Please confirm that the foregoing correctly sets forth the agreement
between us by signing in the space provided below.  This letter agreement may be
executed in counterpart.

                                             Sincerely yours,

                                             drkoop.com, Inc.

                                             By: /s/ Edward Cespedes
                                                 ---------------------------
                                                  Name:  Edward Cespedes
                                                  Title:  President

The foregoing is hereby acknowledged and agreed to as
of the date first above written.

                              Infoseek Corporation, operator of and on behalf of
                              GO.com ("GO.com")

                                        By: /s/ Laura R. Beauchesne
                                            -----------------------
                                        Name:   Laura R. Beauchesne
                                        Title:  Vice President & Deputy General
                                                Counsel

Amount payable as of
the date of this letter agreement
(the "Payable"):                        $1,033,334

Cash Payment:                           $361,666.90
(Due by Deadline)

Balance (Due by Sept. 1, 2001):  $671,667.10 plus 6% interest thereon

                                       2Exhibit 4.3

                    AMENDMENT NO. 2 TO RIGHTS AGREEMENT

      AMENDMENT No. 2, dated as of January 23, 2001, to the Rights
Agreement, dated as of August 17, 1994, by and between Litton Industries,
Inc. (the "Company") and The Bank of New York (as Rights Agent), as
amended by Amendment No. 1, dated as of December 21, 2000 (the "Rights
Agreement").

      WHEREAS, the Company and the Rights Agent have heretofore executed
and entered into the Rights Agreement;

      WHEREAS, pursuant to Section 27 of the Rights Agreement, the Company may
from time to time supplement or amend the Rights Agreement in accordance with
the provisions of Section 27 thereof;

      WHEREAS, the Company intends to enter into an Amended and Restated
Agreement and Plan of Merger (the "Amended Merger Agreement"), dated as of
January 23, 2001, among the Company, Northrop Grumman Corporation, a Delaware
corporation ("Parent"), NNG, Inc., a Delaware corporation and a wholly owned
subsidiary of Parent ("Holdco") and LII Acquisition Corp., a Delaware
corporation and a wholly owned subsidiary of Holdco ("Acquisition I") (all
capitalized terms used in this Amendment and not otherwise defined herein shall
have the meaning ascribed thereto in the Amended Merger Agreement);

      WHEREAS, as a condition of their willingness to enter into the Amended
Merger Agreement, Holdco and Parent have required that Unitrin, Inc., a Delaware
corporation and a stockholder of the Company (the "Stockholder"), enter into the
Stockholder's Agreement, dated as of January 23, 2001, among Parent, Holdco and
the Stockholder (the "Stockholder's Agreement");

      WHEREAS, the Board of Directors has approved the Amended Merger Agreement
and determined that the Amended Merger Agreement and the transactions
contemplated thereby, including the Stockholder's Agreement, the Offer and the
Litton Merger, are advisable, fair to and in the best interests of the Company
and its common stockholders; and

      WHEREAS, the Board of Directors has found that it is in the best interests
of the Company and its common stockholders, and has deemed it necessary and
desirable, to amend the Rights Agreement to exempt the Stockholder's Agreement,
the Amended Merger Agreement, and the transactions contemplated thereby,
including the Offer and the Litton Merger, from the application of the Rights
Agreement.

      NOW, THEREFORE, the Company hereby amends the Rights Agreement as follows:

      1.  Section 1(a) of the Rights Agreement is hereby modified, amended
and restated in its entirety as follows:

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            "Acquiring Person" shall mean any Person (as such term is
      hereinafter defined) who or which, together with all Affiliates and
      Associates (as such terms are hereinafter defined) of such Person, shall
      be the Beneficial Owner (as such term is hereinafter defined) of 15% or
      more of the Common Shares of the Company then outstanding, but shall not
      include (i) the Company; (ii) any Subsidiary (as such term is hereinafter
      defined) of the Company; (iii) any employee benefit plan of the Company or
      of any Subsidiary of the Company, or any entity holding Common Shares for
      or pursuant to the terms of any such plan; or (iv) Unitrin, Inc., a
      Delaware corporation ("Unitrin"), and its subsidiaries as long as such
      entities in the aggregate beneficially own less than 12,658,000 Common
      Shares. Notwithstanding the foregoing, no Person shall become an
      "Acquiring Person" as the result of an acquisition of Common Shares by the
      Company which, by reducing the number of shares outstanding, increases the
      proportionate number of shares beneficially owned by such Person to 15% or
      more of the Common Shares of the Company then outstanding; provided,
      however, that if a Person shall become the Beneficial Owner of 15% or more
      of the Common Shares of the Company then outstanding by reason of share
      purchases by the Company and shall, after such share purchases by the
      Company, become the Beneficial Owner of any additional Common Shares of
      the Company, then such Person shall be deemed to be an "Acquiring Person."
      Notwithstanding the foregoing, if the Board of Directors of the Company
      determines in good faith that a Person who would otherwise be an
      "Acquiring Person," as defined pursuant to the foregoing provisions of
      this paragraph (a), has become such inadvertently, and such Person divests
      as promptly as practicable a sufficient number of Common Shares so that
      such Person would no longer be an "Acquiring Person," as defined pursuant
      to the foregoing provisions of this paragraph (a), then such Person shall
      not be deemed to be an "Acquiring Person" for any purposes of this
      Agreement. Notwithstanding the foregoing, no Person (and no Affiliate or
      Associate of any Person) shall be deemed to be the "Beneficial Owner" of
      or to "beneficially own" particular securities if such Person is the
      Beneficial Owner of or "beneficially owns" such securities solely as a
      result of its status as an Affiliate or Associate of Unitrin and if such
      Person would not otherwise be the Beneficial Owner of or "beneficially
      own" such securities. Notwithstanding the foregoing, neither Northrop
      Grumman Corporation, a Delaware corporation ("Parent"), NNG, Inc., a
      Delaware corporation ("Holdco") nor LII Acquisition Corp., a Delaware
      corporation ("Acquisition I") shall be deemed to be an Acquiring Person by
      virtue of: (i) the execution and delivery of the Agreement and Plan of
      Merger, dated as of December 21, 2000, among the Company, Parent and
      Acquisition I (the "Original Merger Agreement"); (ii) the execution and
      delivery of the Amended and Restated Agreement and Plan of Merger, dated
      as of January 23, 2001, among the Company, Parent, Holdco and Acquisition
      I (the "Amended Merger Agreement"); (iii) the consummation of the Offer;
      (iv) the consummation of the Litton Merger or the Northrop Merger (each as
      defined in the Amended Merger Agreement); (v) the execution and delivery
      of the Stockholder's Agreement, dated as of January 23, 2001, among
      Parent, Holdco and Unitrin (the "Stockholder's Agreement") or (vi) the
      execution and delivery by the Stockholder Subsidiaries (as defined in the
      Stock-

                                      -2-

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      holder's Agreement) of their irrevocable proxies, as contemplated by
      the Stockholder's Agreement (each of the events set by forth in clauses
      (i) through (vi), an "Exempt Event").

      2. Clauses (i), (ii), (iii) and (iv) of Section 7(a) of the Rights
Agreement are hereby modified, amended and restated in their entirety as
follows:

            "(i) the time immediately prior to the consummation of the Litton
            Merger, (ii) the later of the termination of the Amended Merger
            Agreement or the close of business on August 31, 2004 (the "Final
            Expiration Date"), (iii) the time at which the Rights are redeemed
            as provided in Section 23 hereof (the "Redemption Date"), or (iv)
            the time at which such Rights are exchanged as provided in Section
            24 hereof."

      3.  The final sentence of Section 29 of the Rights Agreement is
hereby modified, amended and restated as follows:

      "Notwithstanding the foregoing, nothing in this Agreement shall be
      construed to give any holder of Rights or any other Person any legal or
      equitable rights, remedy or claim under this Agreement in connection with
      any transactions contemplated by the Amended Merger Agreement."

      4. This Amendment may be executed by the parties hereto in separate
counterparts, each of which when so executed and delivered shall be an original,
but all such counterparts shall together constitute one and the same instrument.

                                   * * *

                          [SIGNATURE PAGE FOLLOWS]

                                      -3-

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IN WITNESS WHEREOF, this Amendment has been duly executed by the Company and the
Rights Agent as of the day and year first written above.

Attest:                                 LITTON INDUSTRIES, INC.

By /s/  Lynne M. O.  Brickner           By /s/  John E. Preston
   -----------------------------           ---------------------
   Name:  Lynne M. O. Brickner             Name:  John E. Preston
   Title: Vice President and Secretary     Title: Senior Vice President and
                                                  General Counsel

                                          THE BANK OF NEW YORK
Attest:                                   (As Rights Agent)

By /s/   James Dimino                     By /s/    Steven R. Myers
   -----------------------------             -----------------------
   Name:  James Dimino                       Name:  Steven R. Myers
   Title: Vice President                     Title: Assistant Vice President

                                      -4-

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