Once you've got the watercooling rig, adding a gpu block just a bit more expensive than a decent gpu hsf.
Hose routing, installing/removing a 'blocked' vid card, and pump and radiator capacity become minor issues as well.
That zalman flower is pretty dinky, btw. I was thinking more along the lines of this:
http://www.ocfaq.com/reviews/ArcticC...ilencer_Rev3/2
My 9800 r35 core is watercooled, but I'll certainly be looking for a card that has adjustable Vcore on the next go round.