With that gtx480 and a cpu, a 240 rad could cover it, just don't expect fantastic temps. Decent, better than air cooling, but not fantastic. I would really advise against skythe ultra kazes unless you love the sound of jet engines (for the 3k rpm versions anyways, not sure about the lower ones. or you could put the 3ks on a fan controller). If it were me I'd just hunt around and find some Gentle Typhoon AP-15s - they're out of stock a lot because demand for them is huge, but they're worth the wait.
Instead of 7/16 tubing and 1/2 barbs I'd go 1/2 tubing and 7/16 barbs, you want the tubing to fit really snugly over the barbs. I have 1/2 tubing and 1/2 barbs, and I got metal clamps
to screw on where the tubing meets the barbs, and it's 100% secure - just make sure you tighten the clamps properly with a screw driver (or a socket set if you happen to have one).
Again, what radiator I'd recommend depends heavily on fan speed, and I'd really advise against ultra kazes unless you're sure you're okay with incredible noise (higher fins per inch on the radiator tends to like higher speed fans, lower fpi = lower speed fans), but static pressure on the fans is a lot more important. In case you're not familiar, static pressure refers to the ability of the fan to push air through an object. The reason why Gentle Typhoons make such good radiator fans despite low CFM (compared to a lot of other fans) is their fantastic static pressure.
another thing that's nice about a fan controller is that if you're water cooled, while your computer is idling, you probably don't need the fans on full blast or even on at all to cool things off acceptably. So for me, my fans only spin when I'm in a game, otherwise all the fans are off and all I hear is the pump, which is really quiet. I really like having an almost noiseless computer, and if I leave it on overnight just idling or torrenting/downloading something, I can turn all the fans off and everything still stays chillyEdited by tommy1993 - 4/22/11 at 9:20pm