Danny I've seen that the submerged pc isn't really a good idea of keeping it cool, instead it will just heat up the fluid around the parts unless you stick some massive fans or even a boat prop in to keep te fluid constantly moving.
You could just go the classic watercooling method and then build a case which has a water-tight compartment in with an external water-tight layer where it is filled with liquid so the computer is always seperate however still giving the impression it is in a liquid.
In my head I know what i mean but you may not, will explain later on skype
