The Processor or central processing unit (CPU) is the primary device used to carry a computers functions. The two major brand you can purchase at most computer resellers are Intel and AMD chips.
I purchased an
AMD Phenom II X4 955 Black Edition 3.2GHz Socket AM3 125W Quad-Core Processor, and it has worked wonders. Came with a decent Heat Sink/processor fan and runs everything very well so far. I chose this processor because it came at a phenomenal price for what you get, and had an array of great reviews.