Not a biggie. I flashed my 5870 BIOS to solve an issue with Display Port blinking issue in Eyefinity (now works perfectly).
You want to put their new BIOS file on a USB flash drive and then reboot with the flash drive. To make a bootable flash drive use the HP utility called sp27213.exe You can find it with a quick google search. Then you want to use ATIFlash utility to flash the BIOS. Easy Peasy...