I've got what seems like a similar problem.

XP machine came with XP pre-installed. No XP disc as such but a "restore" disc supplied by Shop.

Can't do a "clean" re-install cos when I restore from disc I get all the crap that the supplier loaded in too.

Having said that when I got XP to the point where it seems stable the built in Restore feature seems to be a reasonable fall-back point if a system file gets deleted or corrupted. Don't think that will be much help if the machine won't fire up in the first place.

Dave Earl