will the vista upgrade for my laptop work for my xp desktop??? Answered

OK, i am not sure but could anyone tell me if the vista upgrade disk i received shortly in the mail after i got my laptop work for my desktop? if it is possible but requires partitioning or hardware/software i need to know those. possibly even could someone create an instructable for this. i would really appreciate your help, even if it isn't possible. keep in mind i am pretty smart with computers but im really young plz help. thanks in advance.