I had good luck with asus suite II software, which includes a windows bios update flash program that you can use while running windows; no usb drive required:
Download<operating system<utilities<suite IIhttp://www.asus.com/Motherboards/AMD_AM3Plus/M5A97_PRO/#download
Can't remember the exact procedure. You may have to download the bios file you need first and save to "documents". The suite II file is large, and includes alot of other stuff, such as hardware monitor software.