What os do you have? 32bit or 64bit?
Do not use AsusUpdate to flash your bios if you are using 64bit windows, it will kill your m/board
I've had no trouble using AsusUpdate with 32bit os, it's simple to use and should be on your m/board support CD
EDIT: This is for your E8600???
Refer to your manual for the methodology on how to flash, if you don't have a manual d/load the .pdf copy from Asus
If you are using 64bit Windows then AFUDOS is probably the easiest to use, you'll need a bootable floppy and a floppy with your AFUDOS & bios.rom file on it
Boot into DOS with the bootable floppy, eject it, insert the AFUDOS & .rom floppy, run AFUDOS as per manuals instructions.
Link one at Asus
Link two at Asus