Before you do anything, mae a BACKUP! Not on the same Harddisk or an other partition of that infected Harddisk! If you do the wrong thing if you try to disinfect the Virus, you can lose ALL your Data!
Do not use old Doscleaner or things like Fdisk /mbr to clean Viruses( at least not on NTFS HDs).
Did you *verify* the infection, do you use a Bootmanager? If you use/have a fast internetconection you can download the Avast BART CD to do the job. But the way with F-prot will do it too.
Anyway, if you cleaned the Virus check all your Floppydisks if they contain the Virus too and change the Bootsequence in BIOS from A: to C:
FMI: Does your XP still boot? I thought Windows should at least alert you that it, at least the Drivecontrol, is running in safe mode