Water cooling is great if you do it for the right reasons. Don't expect to get a better overclock on water than air, thats not always the case, it depends more on your other hardware, and how good your chip is. Many who water cool do it as a hobby for fun, not just for performance boost (in fact many dont even overclock). Its alot of work and maintinence, not for the faint of heart. If your expecting to build it and it just works like clockwork without anymore input for years, your making a mistake. I would certainly suggest getting some overclocking experience on air before jumping into water (if your doing it for overclocking needs). Do your research, its not just about selecting all the (compatible) parts you need, theres much more to know/learn. Its not a 4 hour job, a good setup can often times take up to a week (depending on how much modding you need/want to do), for a first timer, even longer.
"Those folks who try to impose analog rules on digital content will find themselves on the wrong side of the tidal wave."
-Mark Shuttleworth (CEO Canonical/Ubuntu)