im trying to buy a new vid card.. and i was looking at the new geforce 6000 series.. the only problem is it says that they are all pci express.. but teh bottoms of teh cards look like agp so what is teh deal.. do i have to have a mother board with pci express or can it plug into an 8x agp slot.. i was looking at a geforce 6600 or 6600 GT