It depends on the game, some particular games are CPU intensive games and some others are GPU intensive games, the majority are GPU intensive games, but almost RPG games are very CPU demanding such as Skyrim and WOW, Also singleplayer is very different from multiplayer, in multiplayer there are huge maps, lots of textures and packs and a lot of work is done by the CPU, in such a case your x2 CPU will be a major bottleneck.
See the charts below;
In this one, there's no difference between a $100 CPU and the great i7 3960X
look here at Skyrim benches, you need a strong CPU to maintain high FPS
So you'd be better off with upgrading your CPU to at least Phenom II X4