I think my galaxy 6800gt AGP just konked on me yesterday

, was getting 150 fps on cod, now getting 10-20, cleaned it, still getting the same. I think its about time to change it.
I'm looking for a new AGP gfx, but its been long since i last looked at the market price for new gfx (that's how good my 6800gt was). Im not sure waht goes with what, or what is compatible with what now, i need advice
Budget:400-450
amd 64,3200, nf3 mobo with 1 gig ram (DDR)
please quote, cheers