That's a lovely little system, in fact I'd be looking at getting a bigger monitor for it. That rig is more than capable of running all your games at 1920x1080, if not higher.
What FPS would I get on games like Skyrim,BF3,MW3,Black Ops and Portal 2?
See following GTX 670 review for benchmarks which uses an Intel Core i7-3770K @ 4.7 GHz in the test rig. Portal 2 uses the Source Engine which is not very demanding so frame rates should be extremely high.