Most computers have a bios update setting when you turn the computer on - try mashing escape as you boot up. The last BIOS update I did required doing it at the DOS prompt.
Otherwise if you have access to another PC and the discs, you could try Bart's Preinstalled Environment (BartPE) bootable live windows CD/DVD to make the equivalent of a Windows live CD with XP.
Otherwise if you have access to another PC and the discs, you could try Bart's Preinstalled Environment (BartPE) bootable live windows CD/DVD to make the equivalent of a Windows live CD with XP.