When we have LAN nights at my place, it's 6 desktops, 10 monitors, 3 laptops, 2 Xbox 360s and the 42" TV running at once. Think yourself lucky.
Mind you, I do live in England, and it is damned cold right now.
But no, water cooling would probably make it worse, UNLESS it's possible for you to put the radiator for it somewhere outside of your room then it would be greatly improved I think.