Probably one of the most energy efficient processor on the market, but performance wise how is it? I'm talking real time performance, with a GTX 460, i know on benchmark it won't look as good or pretty.
How does this processor compare to an intel core 2 quad Q6600 lets say? or an i5 quad core?
Performance would be more or less comparable to a Core 2 Duo E6600 in games. A Q6600 can easily outperform it and an Ivy Bridge Core i5 would decimate it. In games it depends on what resolution you are going to be playing at. The lower the resolution the higher the frame rates will be and the larger the difference between an Athlon II 610e, C2D E6600, C2Q 6600 and i5-3470 will be.
Overall, it depends on the game. If the game depends on both CPU and GPU, then the Athlon II 610e will be the worst performance; Skyrim is such a game. In games where performance depends on the graphics card (as long as the CPU is not too slow) then the difference in performance will be relatively small; Crysis 2 is an example of such a game.
In terms of overall power consumption an Ivy Bridge Core i5 CPU would likely consume a little less power both while idling and under load.
I am assuming you already have the GTX 460 card. The Radeon HD 7770 provides similar performance while consuming about 20% less power.