An alternative to standard watercooling are the sealed WaterCooling units currently being offered By Corsair (H50 & H70). The newest addition to that same market is now growing with the latest design by Antec featuring their Kuhler H2O 620 unit. Reasonably priced and excellent cooling are just a few of the features you can now add to your system.
I can testify that these sealed systems do live up to the hype and are very much worth a look if your sole intention is performance based. Some people are even modding these to fit there case themes and designs as well as extending the cooling features to other components besides just being a CPU cooler.