A good card for the money is a Ati 4850. It has support for dx10.1 and shader moder 4.1. If you buy one get it with a nonstandard cooler because it is way better.
http://www.xbitlabs.com/articles/vid...s_3.html#sect0
http://www.newegg.com/Product/Produc...on%20HD%204850
Something from Nvidia's side:
http://www.tomshardware.com/reviews/...50,2172-2.html
http://www.newegg.com/Product/Produc...82E16814130464
http://www.newegg.com/Product/Produc...ce%20GTX%20260.
A word o caution when you buy a video card because the new ones are in need of some quality power supply