XP Blue Screen of Death, Inaccessable Boot Volume or other nonsense
First, try to boot in Safe Mode by pressing F8.Then, try booting from your XP CD and either Re-install or try the follwing.
Go to Recovery mode
Type the following commands
CHKDSK C: /r
CHKDSK C: /p
fixboot
If you STILL have problems you can try this last ditch fix:
Boot off the XP CD into recovery mode
COPY K:\i386\ntldr
C: COPY K:\i386\ntdetect.com C:
ATTRIB -H -R -S C:\boot.ini
DEL C:\boot.ini
BootCfg /Rebuild
Good luck!