What Can I reasonably expect out of my current rig?

Recently I was able to ditch my old Pc I was using as somewhat of a place holder for a better more up to date PC, but I'll admit I'm not as PC Savvy as I should be. My question is basically, what can I reasonably run on this Rig without falling into any real issues in terms of FPS,etc ( would hate to invest money into a game thinking I can run it, but fall short ).

Processor- Intel Core i7 960 3.20 Ghz

Ram- 6GB

OS- Win7 X64

Video Card- Nividia GTX 560 Ti

I've tested it out some but curious what my ceiling would be on it as I don't do crossfire with it and didn't do a upgrade to 8GB Ram either ( Obviously ). Power Supply is only 700 Watts as well.