I hope you have licenses for those multiple Windows XP installs. If not, you are committing software piracy, a problem for which you will find no help at TechIMO.
Anyway, you will need to create a bootable DOS disk (floppy, CD, etc.) containing the the BIOS update and an appropriate BIOS flash utility for your motherboard. Boot the disc, then load the flash utility and update via a DOS command line operation.
As for whether a BIOS update will resolve your issue, it is not likely. Your problem is most likely elsewhere, such as a BIOS configuration issue.