Should be same for Win2000 make a boot disk copy files to it restart and type K8V1005.exe at the a: prompt. The executable is so you don't have to type your flash commands manually. Asus already made the executable for you. Make sure to remember your settings in bios since they'll probably be reset to default.
Asus says not to use the Windows flashing program. "Please flash BIOS using K8V1005.exe, and do not flash from 1001, 1002 or 1003 to version 1004 through EZFlash/AFUDOS/LiveUpdate"