You can get even more cards if you don't want to go PCI. They have the FX6800GS and the FX7800GS.
For me, I won't go back to PCI. I look at it, they started out with PCI. Then they went to SLI. Then they went to AGP. Then to AGP4X then 8X. Now they went back to PCI again. IMO, I'm just waiting for when they go back to AGP again. Which trust me won't be that long.