"Trying to lure more people into watercooling their PCs, Corsair have created the Nautilus 500. It consists primarily of an external unit housing the radiator, reservoir and pump, which sits atop the PC's case. Installed inside the PC is the CPU water-block, which can be fitted without removing the motherboard. At HEXUS we've got pictures from CES of a system with the cooler installed."
3M Fluorinert PF5080 is the one you want to be looking at Ed if you ever did go the water route, although it is expensive. As long as you know what you are doing with the equipment and take the neccessary prcautions (leak testing for 24 hours before it comes into contact with your rig) then you'll be fine. Using slightly smaller diameter tubing than normal (7/16 instead of 1/2") is a pretty much foolproof way of not having a leak down to user installation error as the tubing has to be heated before it can be pulled over the barbs and once it is in place it wont come off unless you cut it off It also allows your tubing to bend quite a way without any kinks which is essential if your running an SLI setup.
I'll have to post pictures of my new rig when I get round to modding it.