There's only a couple people here who know fairly well what goes into a water cooling setup. I thought that we needed a nice indepth guide to water cooling and have it a sticky along with the Overclocking guide.
No I'm not writing one myself
Please go to the link(s) below regarding any and every water cooling question you may have. It is very thorough and well written.
Here is a little guide that is an update to Nubius' water cooling guide. This also covers leak testing, and will be covering coolant in due time. Coolant is certainly one thing that is overlooked by nearly everyone who watercools.