warmon06 got what I was saying. i7 is indeed a powerful CPU, but most of it's power goes to waste if the user is just going to play games, meaning wasted money. Though more games have been optimizing dual or even triple cores, most games don't benefit quad core users. This may change in the future, but as for now, the most demanding PC games are sadly console ports.
The i5-750 is probably the best option for a gaming rig. It's powerful enough to match an i7's performance in games, aside from the little performance it loses during Crossfire in 8x/8x mode, but what's a 1-3 FPS loss compared to a $100-200+ price premium of having an i7? The i7 can support 8-12 logical cores and have triple-channel memory, but those have no real benefit in gaming, so there's no real reason to get an i7, unless you're doing extensive video-editing, programming, etc.