Im curious what type of water are you going to use in it, normal tap water or distilled water?

i was planning on using distilled water with some kind of glycol based antifreeze.

a little idea: if i seal my case completely airtight and put some kind of humidity sucking salt in it, would i have to worry about condensation ? All important heatsources would be cooled with cold, but above-freezing water (CPU, GPU,Chipset, Mosfets and maybe even PSU).
I think if this works its easier than to mess with insulating everything.

I don't know how effective that dessicant can be, but I do know that it needs replacing regularly (i.e. stick it in the oven, to dry it out again).

Personally, I wouldn't trust it.

Im sure you can test it yourself, i used to remember the infant school science tests. Get a glass of cold water from the fridge, and put a piece of cardboard over it. You should get condensation forming fron the outside of the glass because the water inside is cooler... Now try the same with salt water, if you get condensation then u'll have answered your own question.

The cardboard was only used to show water not escaping from the glass.

That would work, but it would be a pain in the arse. You're better off just insulating everything pelt style, and wrapping the tubing up with those styrofoam pipe insulation tubes and duct taping everything tight and sealed. You wouldn't believe how many things would need to be cooled to be able to seal up your case without risk of burnout.

I have a sticky "I" key. Drives me nuts.

yeah if i rethink it, it probably wont be easy to get it 100% airtight. does anyone have a link for a good insulation article ?
i would even have to insulate the bottom of the cpu block that touches the air. And same for the mosfet block, because the contact is not 100% like with the chipset and GPU. Another problem is the backside of everything.

Check the phase change forums here and on oc-forums for loads of info.