David: a 12v PC fan will do perfectly.
if you need any help at all with watercooling feel free to PM me.
i've included a few pictures of my current pc watercooling setup just so you can get an idea of whats going on (ignore the dust)
my first watercooling setup was actually using a 2600lph pond pump and full size radiator out of a camry and my waterblocks (heat exchangers) i made myself with 6mm copper plate, 20mm plexiglass and a dremel