Air cooling is widely used even though water cooling yields better results it is expensive and even you do not know what you are doing it is easy to damage or ruin computer components, there is liquid involved after all.
A solid case with good airflow and a HSF that provides good cooling is basically the only thing you need. The C2D duo chips make overclocking simple, even with the standard HSF that comes with them people have been getting great results with minmal effort.
Good HSF.
http://www.newegg.com/Product/Produc...&Go.x=0&Go.y=0