Duckmeister's statements about the performance of AMD CPUs in combinations with modern GPUs is entirely inaccurate. I'm not sure if he is trying to be humorous about it, "trolling", or is just plain misinformed.
In any case, the i5 750 or any of AMD's high end quad core Phenom IIs are excellent choices for gaming computers.
With regards to the i5 vs i7 argument, a bit of clarification is in order. There are two distinct platforms to keep in mind; the P55, and X58 chipsets. The former can use i5 and i7 CPUs designed using the LGA1156 socket design, the latter uses the LGA1366 socket design. Indeed on the P55 platform the primary benefit of the i7 CPUs is that hyperthreading is enabled which can benefit certain applications, although typically not gaming. Now, on the X58 platform which uses its own selection of i7 processors, there are several extra benefits over the P55 chipset. The main two that come to mind is support for two full x16 PCIe slots (useful if using two high-end GPUs) and the option of using triple-channel memory. These features are of little concern for low-to-mid range gaming computers and as such the P55 chipset and the quad core i5s that accompany it remain excellent choices for the budget gamer.
The Phenom IIs are also quite good and can certainly be more cost-effective than some of Intel's offerings. I believe AMD is set to release a new 6-core CPU in a few weeks that will be reasonably priced.
