Have you done a search for Koolance on this board yet? I've seen several threads on Koolance here as well as on Bit-Tech, [H]ardOCP, Pro-Cooling, etc.
And yes I have one (the larger case). I've posted fairly lengthy discussions on pros and cons, but I don't think it was on this board.
Short story: it's an easy and effective turn-key system. The electronic temp monitoring and control is nice. You could probably do better by building your own, but it's a matter of what you want and what you're comfortable with. I moved all my compoennts and had it up and running in about 45 minutes. It amazingly quiet and held my 1800+ and GF3 (both overclocked) at fairly low temps. Since I'm in AZ and not running AC yet, it's fluctutates noticeably with the ambient air temp (1 small room, 3 monitors, a laser printer, and 3 computers, all athlons = WARM). I've seen it as low as 23C and as high as 38C on the waterblock temp sensor. Load only fluctuates a degree or two.
Having said that the other 2 computers water cooling systems will be self-built (still waiting on parts) because I want to experiment.
This was a longer post then I meant to get into.