my opinion of current AGP options would be the Sapphire X800GTO (I bought one earlier this year). You won't have pixel shader 3 capability, but as a result you save the extra workload it would otherwise need to process for it. It has GDDR3 memory (why is the x1600 only ddr2 when it's newer???), and can be significantly overclocked even with the STOCK cooler! Why Sapphire's x8xx series coolers are better than ATI's is beyond me! I switched to a zalman cooler and only gained marginal increase in max overclock, with about a 10 degree decrease (does'nt hurt).
looking at the VGA charts it is roughly equivalent in performance to the 6800, depending on what game you are playing (although hard to know for sure since it was not reviewed for some reason), but does not have pixelshader 3. The difference in these technologies is marginal right now, and you would likely not miss it (I don't).
With 1gb of RAM and an A643200+, I can play BF2 on all high settings, but no AA/AF. If you really want AA/AF in an FPS, save up and get a PCIE 7800+ card. Personally, I have seen them side by side at LAN parties, and I am SO glad I saved the money and stuck with AGP for now. I can't see the difference.