This may be a moot point now if you've returned the PC, but were any other PCI cards installed in the system, that you could verify the PCI bus was operating properly?

Not sure on the Sapphire, however the FIC AT31 "Fusion" also uses the ATI 320 northbridge, however makes use of the VIA southbridge as ATI did not have the chipset completed in time.

You would need to install both the ATI chipset drivers and also the VIA 4-in-1 chipset drivers to get both bridges functioning correctly.

And as has already been said, onboard graphics are generations behind the "standard" add-in video card of the day. Even the latest nForce2 IGP boards use the meager GF4 MX graphics. IGP boards are not designed to be gamers by any stretch of the imagination. They're aimed more at "value" systems and OEM builders.