When building a gaming PC, people often try to go with the most powerful processor they can afford. They'll go with a higher-end AMD processor or a Core i5/i7. While this is necessary to get those Ultra graphics settings, it's not necessary to get medium to high quality graphics for most games, even some of the more resource intensive ones. The fact of the matter is that GPU matters far more than CPU. You can save a little cash by opting for a lesser processor. Even a low-range Intel Celeron can manage a game like CoD Ghosts as long as the GPU is fairly high-end. The Celeron costs $55, while an i5 processor can cost over $200. It's just a simple way to save some decent money without suffering a crippling blow to graphics output.
Very Good tip. It's a good idea to have the knowledge of what sort of games you want to be playing and ultimately what you want to be doing on the computer. For instance, if you want the computer to be a streaming computer, something that's become very popular, then an expensive processor is something you'd want to invest in. But for a majority of games, as you mentioned, don't need that insanely high-priced and top end processor to be a good productive computer for you.
