Go to any computer running Windows 95/98, and make an MS-DOS startup disk.
You can do this by formatting a disk, sticking it in the floppy drive, going to a command prompt and typing
sys A:
This will make a basic MS-DOS startup disk. Now, take it to your Windows 2000 machine, dump the BIOS update program and BIN file onto the floppy, boot off it and update the BIOS.
[Windows XP can also make an MS-DOS startup disk, to do it, right-click on the floppy drive and select "Format," and then check the "Create a MS-DOS Boot Disk" box.]
You can use the WinFlash BIOS Update Utility if your BIOS supports it. This nifty utility lets you update the BIOS from Windows. They'd say something about that on the board manufacturer's web site, probably, if it was compatible.