From what you told me, you edited the BIOS and the CD drive no longer worked... Now revert that change... Most BIOS versions should have a command "set to factory defaults", or something along the line... select that command and save and exit... That should configure your CD drive to be one of the boot devices... The put the XP Install/Repair CD in, reboot the computer... it should now boot from the CD... then you should be prompted to select whether you want to install or repair your system...although it may be better to do a format/install, if you are worried about having to lose the data, select repair or clean install. The setup instructions should walk you thru the process... Good luck.