Aside from cooling, that would actually look really cool as is. You know how light difracts through water? Everything in the PC would look all ripply, and then perhaps you could undo the screw at the top of the case and put in yellow or blue dye, and have the case "immersed" in this colorful wavy goodness.
Yeah, the cooling would be a failure. Well, actually, perhaps the case could provide as some sort of water cooling radiator and pump by itself and will come with tubing to plug into the components. If you have another water coolable component, undo a water-blocking plug on the interior of the case, and attatch a tube to go to a component.