Here's one for cheaper that $200 9800GTX+ and give's you pretty much the same performance. Plus this 4850 comes with a zalmen cooler!
Here's proof that the 4850 does give quite competitive prefromance compared to the 9800GTX+ just pay attention to the resolution. I doubt you will be playing at 1600x1200.
Another Pro to going ATI is that they update the drivers every month or two which always increase preformance, so often that I'm behind by 3 driver versions because I just looked up the most recent drivers.
Nvidia updates them every six to 12 months. :O