I need a new graphics card.My Mobo is an Asus P4S8x.While browsing through my BIOS settings(with a deep look of Puzzlement)I noticed I can set my Primary VGA BIOS to AGP or PCI.
Does that mean I could use a PCI-Express card? And if so would there be any advantage over using the AGPslot which is8X??

No. You can use AGP or PCI (not PCI express).

PCI is not the same as say PCI-E 16x. Yes, you can put a PCI video card in there but it would not be PCI-E.

Just over a year ago I upgraded my mainboard and my processor. At the time PCI-E was just starting to hit the channel (and I was unsure of the technology). Given the limited amount of PCI-E video cards I decided to stick with something that had an AGP slot so I could use my 9800 Pro.

I absolutely regret that decision.

PCI-E video cards are now the norm and (in many cases) are cheaper then their AGP equivalant. Not only that, but the PCI-E cards are faster and there are more chipsets made for PCI_E then there are for AGP (ie x1800, and x1900 from ATI are not even available for AGP and NVidia only recently produced a 7800 card for AGP).

My advice????

Buy a new Mobo that has a PCI-E 16x slot as well as a PCI-E Video Card. The short term will be just a little more money for the Mobo addition, but I think you'll find it worth it. After all, as it is you'd pay a premium on the AGP card.

The dirty deed is done!!Bought and installed Asus 6600gt.Works real fine on the 300w PSU.