Liquid cooling is a great way to both increases the cooling capacity of your computer, giving it the opportunity to be overclocked more, and make your system quieter at the same time.

Thermaltake has a good quality liquid cooling system that comes with all the components you need in one box called the Bigwater 745. The Bigwater 745 sports two radiators, one 120mm and one 240mm, for peak cooling performance.
Review excerpt: "The CPU waterblock that Thermaltake uses is an acrylic topped unit with a blue LED to illuminate the block when power is on. The base of the waterblock is made from solid copper. Looking at the bottom of the waterblock, it is highly polished and had no noticeable nicks or scratches on the surface. Light machine marks were noticed on the contact surface of the block. The circular portion of the block is to ensure compatibility with Intel BTX. In addition to BTX the block is also compatible with Intel LGA775 and all AMD K8 series CPUs." Read the full review here.