There has to be a better way
Are you sure you need to update the bios? why?
have a HD sound problem updating the bios fixes that problem
I have a different Asus mainboard, but it also uses EZ Flash 2. I prefer to use it rather than flashing the BIOS from within Windows.
(I have an external USB floppy drive that I could use, in principle, but the BIOS files are getting to be too large to fit on the DOS-ish floppy that Windows can create.)
Basically, to use EZ Flash:
Extract the BIOS file to a USB flash drive.
Reboot the system. Enter the EZ Flash utility by pressing alt plus F2. (Can also be done from within the BIOS setup.)
Select the USB drive with the BIOS on it by pressing the tab key.
Once you're on the USB drive, the utility will find the BIOS update file, and all the rest can be done with the enter key.
This is covered in the manual that's available for download (as an Acrobat file) from support.asus.com, if you've mislaid your paper copy.
Note that it's possible for a failed BIOS flash to render your system unusable. Asus has a BIOS recovery tool (CrashFree), but there are no guarantees that it'll work. I haven't checked whether your EEPROM chip is socketed, but mine (P6T Deluxe) isn't. In the worst case, the mainbaord would have to be returned to Asus for service, as you couldn't swap chips.
That said, I've never (in 14 years) had a BIOS flash fail to the extent that the PC wasn't bootable. I have read of a BIOS flash that failed because the owner's dog pulled out the power cord in the middle of it, but most people manage to avoid that sort of thing. Don't flash during a thunderstorm, for example.