When would you be upgrading the GPU again? If it's not going to be for awhile, I would go for an i3 and pump more into the GPU, possibly building it all but the GPU and waiting on the 78xx, or possibly a 7950 with the money saved in February and buying the i5 2500k now(if you are going to have more money in the next few months that is).
If the budget is pretty set in stone the 2500k is a little more then you need for that class of GPU. You could also try a Phenom II 960T, which can hit 4Ghz+ easily and possibly unlock to an X6 for $130, though it would be a little slower in games like Starcraft 2.
2500k is a phenomenal processor but not at all necessary unless you are running high end GPU setups. Your GPU won't hit the frames an overclocked 2500k could potentially produce.
After it's built no upgrades for the forseeable future, if ever. Really this is all just to play SW:TOR, and watch anime/browse gaf on.