PCI/e will run circles around AGP all day
Actually, it doesn't. About a dozen hardware review sites matched "identical" AGP and PCI/e cards against each other and AGP was actually faster in many cases. PCI/e looks faster because the vid card manufacturers deliberately crippled their AGP versions by reducing clock speed or eliminating key features, and eventually simply quit releasing AGP versions of their cards.
The PCI/e bus has a few things going for it. Although it is in fact a faster bus, the bus speed still did not materially affect the overall speed of the card (including image quality and framerates) through the nvidia geforce 7xxx series cards. On the other hand, pci/e is more flexible and expandable, and with the last several generations of motherboard chipsets, it is cheaper to implement.
I guess if you're a motherboard designer or a marketing droid, pci/e really is better than AGP, but if all you have is a single graphics card then an AGP version would be essentially identical in performance to an pci/e version. You can say the improved bus speed would make the difference, but the fact is that it doesn't make a darn bit of difference. The AGP bus has some efficiencies that the pci/e bus does not, and the really important factor is how fast and efficient the memory located on the video card is, not the bus speed.
I've seen the numbers, and they were duplicated by a number of independent web reviewers.
