Read this review:
http://www.anandtech.com/cpuch...c.aspx?i=2275&p=10
The XP3200+ is able to give acceptable FPS in all situations at these. CPU being the limit is not a significant problem in most games.
What's important to note here is not that the XP3200+ is at the bottom in all tests, but the actual FPS. In almost all cases these are totally and completely playable Frames per Second. Other CPUs are "better" but often you're talking at levels imperceptible to MOST people. For the most part, FPS below these levels will be primarily graphics card induced... and most people use resolutions and AA/AF levels that create a graphics card limitation rather than a CPU limitation.
In other words, buy the best card that fits in your budget, don't worry about your CPU limiting you, because you'll likely crank up the graphics to a place where the GPU will be the limitation anyway.
CPU limits are fairly independent of resolution. That is, as you go to higher resolution CPU is less likely to be the limit and the graphics card is more likely. In the case where you want 10x7 or 12x10 and maybe some AA/AF it depends on how much you want to spend, but the 6800 is about the lowest I'd consider. A 9800 PRo is good if you're on a tight budget, but I wouldn't buy a new one at this point, there are plenty being sold used as people move up. a 9800 Pro will definitely not be limited by CPU at 1024x768 + AA/AF