You may want to know:
How to update the bios? Please click here.
Besides downloading the bios file, you also need the Flash Utility to flash bios rom. (For files before Aug 2001)
For more FAQs about BIOS relationship, click here please.
You won't need to update BIOS until the latest bios has improve / fix some functions.
You won't need to upgrade through all of the BIOS files, just upgrade to the latest one please and it will include all previous improvments.
The CMOS data will be lost after flashing the BIOS. You may need to enter the BIOS setup screen and configure your system information after rebooting the machine.