It also depends on your gaming quality and resolution. However Skyrim is only optimized for two threads so your fine. But In order to not bottleneck high end cards it is best to use a quad core CPU. Also, I would hold off on the 560 Ti. Kepler and Radeon 7800 series is right around the corner. They offer better performance at the same price range.
Hard to say exactly what that setup would do, but I'd expect some significant bottlenecks from that CPU, especially with Skyrim. Is it a black edition cpu?
Assuming you have a socket AM2+/AM3 motherboard, I'd recommend picking up a phenom 960T for ~$125, a Hyper 212+/evo cpu cooler ($30/$35), and overclocking that to 4 GHz or so, which should help remove CPU bottlenecks.
:edit: Don't pay too much attention to the absolute fps numbers in tomshardware benchmarks of Skyrim, though. They didn't use any of the available CPU optimization mods (skyboost/tesval) and so they get pretty bad performance. My 960T, unlocked and OC'd to 4.0 GHz results in minimum framerates in the 40s with 1.3 skyboost (paired with a 7970, 1080p with all settings & AA maxed).