As plumboby mentioned, the biggest difference between the desktop i5's and i7's is that the i7's have hyperthreading. That means that for every physical core they also have another "virtual core." So both the i5 and i7 are "quad-cores" but the i7 has 8 threads, meaning it can perform multitasking better. However, most games these days aren't able to take advantage of 8 threads, and probably don't even need more power than that of a decent i5. Put your money into a better graphics card ;-)