- Tweaktown compared all eight of the current AGP graphics from ATI and nVidia including :

Radeon X700PRO, X800XL, X850XT, X850XT PE and
GeForce 6600GT, 6800, 6800GT and 6800 Ultra

excerpt:

As much as ATI and nVidia wish they didn’t have to worry about the aging AGP connector anymore, there is no denying that there is still a big market out there for this platform. While the PCI Express equivalent to its AGP counterparts might be slightly cheaper (since the AGP versions require bridge chips), the cost of moving to a PCI Express based system is much greater with items like motherboard, memory, CPU all possibly needing an upgrades as well. And this is why we are still seeing current AGP graphics cards on store shelves.