Alright, check out this build: http://pcpartpicker.com/p/YO5m
There is no reason to get an i7 if all you will be doing is playing games. The i5 I have on this build is the top i5 chip and it is really the #1 choice for people who are building a gaming PC. I can also tell you that the graphics card that I chose is probably very similar to the graphics that they will be putting in the new generation of consoles. I did what I could to find combos and discounts and the best deals possible, so if you dont like the mouse or the case, feel free to change it, but I think that is a pretty solid build considering I included a 23" Samsung Monitor...personally I own the 27" version of that monitor and its amazing, I always recommend the Samsung SyncMaster.