The basic GT shoudl be more than fine. I have an older X1800Pro and it runs FEAR at maximum settings just fine. 30-40fps all the time with all the goodies at full blast. You really don't need a massive card to play games these days. You just need to set up the thing correctly.
1:Download and install a utility call ReForce. Set all of your refresh rates for Windows to 60hz and lock them there. Leave the video card's refresh rate alone - it will only see 60hz anyways as an option after a reboot. More than 60fps is wasted, visually, so there's no need to ask your monitor or card to do more than that.
2:Set the thing to 16 bit color. Unless you are using Photoshop for editing photos and such, you'll never notice the difference playing any game on the planet. Even as little as 5fps is enough to where your eyes won't tell the difference. Also turn on trilinear filtering - most games default to bilinear.
3:Set the video card settings to maximum performance other than texture quality, which should be set to quality. Set the rest to application controlled. The idea is to get the card to run as fast as possible yet look good for static stuff like backgrounds and long-range stuff. So that when you DO stop blowing up aliens for a few seconds, the world looks like a proper world.(FPS drops because you hit a lull, quality settings take over)
4:Play all games at no larger than 1024*768 - give or take. Most textures are optimized for this resolution. Turn off AA in-game. It honestly isn't as important as lighting effects and anitstropic filtering. Proper lighting is by far the most important effect in a game as far as making it look realistic.(HDR and such) Second is the Aniso, because it makes lines and geometry look proper in the distance.
http://en.wikipedia.org/wiki/Anisotropic_filtering
Go frugal with your settings in order to crank this up to 4x and add in HDR:
http://en.wikipedia.org/wiki/High_dynam ... _rendering
These two together are addictive.
Far Cry is a fantastic game with the visual effects at maximum. I play it and just wander around sometimes. I especially like the second or two it takes to adjust from a light to dark place and vice-versa. FEAR's enemies seem to be able to see in the dark. Far Cry - they also will get blinded and won't see you in really dark shadows if it's on.