Medicare Drug Card Guaranteed Savings Act - Amends part D (Voluntary Prescription Drug Benefit Program) of title XVIII (Medicare) of the Social Security Act to provide for the offering of a Federal national prescription drug discount card program. Charges a $30 fee for the card under the program. Provides for direct negotiations by the Secretary of Health and Human Services with prescription drug manufacturers to obtain discount prices that are to be less than prices otherwise available in the retail market. Provides that: (1) for periods beginning with January 1, 2005, the only discount card program in which an individual may be enrolled shall be the Federal national prescription drug discount card program; and (2) individuals enrolled in another program as of December 31, 2004, who do not affirmatively disenroll from all discount card programs are deemed to be enrolled in such Federal national prescription drug discount card program.