I have a 2900pro 512 ($350) in my second gaming box and it runs all the latest gaming titles fine. It's basically an underclocked 2900xt and I haven't seen need for overclocking it so far. The image quality is superb and speed comparable to my 8800gts. It probably is a bit slower than the gts but it's cheaper too.
Just be aware that you need dual pci power outlets and 600W power supply when running a SINGLE 2900xt. They draw power like crazy. The exhaust from my computer is hot like a sauna while gaming.