With game consoles having 8 core x86 processors, games are bound to become more multithreaded (use more cores, in other words). I'd go with an i7 at this point then, because it uses hyperthreading. Hyperthreading is basically when each core of a processor "pretends" to act like two cores. Thus, a quad core i7 will act like it's an 8 core processor instead. One hyperthreaded core good as having two actual separate cores of the same architecture, but it's better for more multithreaded games and applications than just one normal core.
I think it's a valid question because just a few years ago, games weren't very multithreaded. Most were console ports, and you could match or exceed the performance of consoles easily with minimal multithreading in the PC port. Thus, an i7 didn't have really any practical advantage over a similarly clocked i5 with regards to gaming (especially the unlocked chips; you could easily set the clock speed of an i5-2500k to match that of an i7-2600k), and the i5 was the better purchase. And again, that's going to change as games continue to be made for the eight-core Xbox One and PlayStation 4.