Ok,

The way I understand it is this....

PCI-Express is going to be the new industry standard and you will see more and more computers with this architechture. On the new MOBOs you'll have a series of PCI express slots, and one of them will be the one for the video card. It's supposed to be as fast as, if not faster than AGP for video and the rest of the slots will be backwards compatable with existing PCI technology. The idea is to get rid of the PCI bottleneck that we currently have on our systems. PCI express MOBOs will NOT have AGP slots.

The ATI card numbers work like this:
9600, 9700, 9800 = AGP cards
X600, X700, X800 = the equivilent cards, but they are the PCI-Express version.

I don't know how nVidia is handeling this.

If I'm wrong, someone please correct me.

HTH,
Todd