Don't be frightened of the bios, it's all basic stuff in there,
yes you could screw up the pooter, but you'd have to be changing lots of things at once for no reason to do so, and even if u did, just set them back to normal next boot,
anyhoo, get into bios the usual way... F1 at start up usually,
then navigate thru the screens, theres help on the right hand side of the screens telling you what to do, obviousely you have to use the keyboard as mouse dosent work till drivers have loaded.... sometimes a usb keyboard wont work on the bios, but nowadays they tend to.
When you get to the setting for enable or disable onboard video, or slect the adaptor to use, change it to suit, i.e. if it's enable or disable onboard video, set it to disable,
if it's select the adaptor to use, select the avga one... may be listed by the slot type..... i.e. it'll sya onboard, or AGP/PCIe slot,
save and exit from bios, and hope it works.
i must admit i had problems setting my avga 3000 up, was running xp sp3, 32 bit, and it screwed up as i was using an anologe monitor via an adaptor on the dvi port of the avga,
the latest drivers sorted that issue out for me, but the web page with the updated drivers isnt publicaly accessable... or it wasnt a few months ago when i needed them, but a few people have posted here they are on the ultimarc site.