All the major computer manufacturers have BIOSes available for download.
Follow the directions on the web site.
It's extremely unlikely that the battery on your motherboard will fail,
unless your computer is many years old. If such a battery does fail, it's a
simple job to replace it. After you replace the battery, and presuming that
your computer is not otherwise damaged, you simply restart your computer
with the BIOS diskette in the drive and your BIOS is restored.
I am not aware of an application that backs up your BIOS, although it's not
hard to piece together what's in the BIOS with XP's System Information tool
or third party software. However, in less time than it would take to read
through System Information or to locate and install third party software you
can simply copy down the information from your BIOS screens with pen and
paper.
Modem Ani