XP has a repair function, assuming you have the original xp disk, you need to boot from said xp disk carefully monitor all actions till the recovery screen appears, press R for recovery, you will be asked which system you want to recover press 1 you will then see enter administrators password, hopefully there isn't one,
you will then see C/: windows you type chkdsk /r
C/: windows chkdsk /r
press enter, let run till you see C/: Windows you type exit
C/: windows exit
pc should boot and run a lot better.
you may need to adjust boot order to cd/dvd
to boot from xp disk
screbo, November 2009