I'd imagine, you could you a little of each, if you wanted. For example...you could have your CPU water cooled, and have your case, board and vid. card air/fan cooled.
Well, I'm not sure there are any other choices for cooling. The three types of cooling that i know about are water, air/fan, and passive/heatpipe... the latter is the quietest, but also not as effective as the first two.
that is what i mean... i dont want to experiment with watercooling till i get a new pc and can risk this one... but i caint cool much more with air and it restrics my over clocing capabilitiys... i have a p4 2ghz oc at 2.4 ghz any more and i crash