Only if you intend to overclock. If you have no intention of overclocking your PC, then the stock fans/cooler will be more than enough.
I enclosed a CPU cooler link down below. If you have questions, this will probably answer them. If not, you will definitely learn from it. And if you have question that can't be answered, just post back and I'll be happy to help.
UPDATE: If you do decide to go with a CPU cooler and intend to overclock, I have a couple of suggestions. The first suggestion would be for if you intend to overclock from the light to medium range (.1-.4 Ghz). A good option there would be the Cooler Master 212 Evo, which is an air cooler. Here is a link...