Is it asking you to disable the BIOS? That error is a driver/software conflict, normally. At least, it was in my old, old computer 8 years ago when I fucked around with pirated windows and a stolen external DVD writer.
Could also be a memory problem.
How old's your computer?
As to reinstalling XP -- I'm sure there are backup programs that can dump everything on an external harddrive and then put it back onto the main computer again. Don't know anything about that, but I'd be shocked if such an option didn't exist.
Though I'd explore the software/driver/memory issue first.