At a res of 1440 x 900, would i see any difference with the either the 9600gt or the 8800gt? I dont play many games, mostly 2142, and i'll load a FPS here and there to try out. My CPU is a dual core amd opteron (939) so I'm sure it's a bottleneck.
I have the 9600GT and I run 1440x900..for anything but crysis it has been able to run on high or max settings at decent framerates. I don't know about bf2142 but I run C&C3 at max settings and I hit the 30fps cap.
The 8800GT is better but also more expensive. Both cards are approximately the same price/performance so go with whichever matches your budget.