I have both of these cards laying around and am trying to decide which to run in my PC. The 7900 is a little older so I'm having trouble finding a direct comparison between the two. Does anyone know which is a better card?
The GTS 250 is essentially a rebadged 9800GTX+. It offers significantly better performance than the 7900GT.
Here's Tom's graphics card hierachy chart to give you an illustration of where these cards lie.
For a more direct comparison of relative framerate, choose the benchmark from the list. Both the 7900GT and 9800GTX+ (GTS 250) are represented.