I'm in the same boat you are.
Well I guess you could wait for Nvidia to put out a 6600 card in AGP. I've seen the PCI express version of the vanilla 6600 for about 130 bucks on up on pricewatch.com. I have no idea if that card is going to be made into an AGP format though. Anyone know??
this is what I'm talking about
You could go with a 6800 but that's going to cost you. Personally anything more than 200 bucks on a video card is hard for me to justify.
That may make me go to a 939 board with PCI express instead of a socket 754. I'm gonna wait till after Christmas though to build.
Personally from what I've read and been told if you're thinking the last generation of video cards go for the Radeon ATI 9600- 9800 series instead of the Nvidia GEforce FX 5200-5900 cards.
If you want the newer cards then go for the GeForce 6600-6800 cards because they seem to perform better then the ATI cards.
As for the 6600 card....
This is what I'm talking about