Re: 128 AGP vs. 256 PCI BUS video card???
Well, put it this way, the maximum throughput of a PCI bus is 133MB/s, AGP x 8 is around 2GB/s. Huge difference. And also the fact that all PCI slots share the same bandwidth, you looking at about 100MB/s depending on whats connected.
This plays a major part in performance. So, really, you can't compare the ammount of memory a card has to compinsate. Try Unreal Tournament 2003 on a Radeon PCI 256MB Card and compare it to a 64MB AGP version. The AGP version would win hands down.
As Jay says, there's no point in PCI Graphics cards today for home machines. The advantages of PCI Express over AGP are just being noticed with todays Highend cards. PCI Express 16x has a Bandwidth of 4GB/s, twice that of the AGP x8 Spec.
Delta: "What's wrong Chris?? Chris: "I miss my old Cyrix"