The best thing to do when looking for a new video card is to search the net for reviews that pit several cards against each other in various benchmarks. The video card industry does a good job of clouding the issue with tons of versions of similar cards all with *fast* sounding names like Ultra, GT, Pro, and Gold. It's a nightmare for the casual buyer.
So look for benchmarks on respected sites, pick your price range and then start hitting all the online stores to see who has a good deal on what. Then just before you buy, double-check with people that are in the know (like people at these boards) for anything you may have missed.
One example is the presence of some cheaper ATI 9800 Pro's (Atlantis) - they're cheaper because they have a lower memory bandwidth (128bit vs 256bit). They don't have less memory, they have slower access between the core and the memory which directly impacts your frames per second. Little details like that will make you think you've saved $40 when really you've got exactly what you paid for; a lesser product.
Good luck.
