I am on my way to doing watercooling right now. It isn't necessary but it is fun and will let me get a little more performance out of my equipment. I already have some of the stuff and the rest is in the mail right now.
I agree with Silk. I wouldn't do the Koolance. I mean, I'm sure it works, but probably not much better than a good air setup, yet a lot more money. I went with Danger Den stuff for pretty much everything.
By the way, if you haven't seen one of these yet check it out. I just ordered one because I liked the idea.Swiftech MCRES-1000P