Keep in mind that once you go watercooled, and you have the pump rad and the block in place, whenever you upgrade you wont have to repurchase the entire kit. You will just need to replace the block of the item that you are cooling (eg. in this case the cpu). In terms of noise, air cooling cant even come close to water. Those huge air coolers with 120mm fans on them make a racket compared to the setup that I have. In fact, during the Winter, I can pretty much shut down the fans on my radiators and run passive (though I do have 2 radiators to pull this off).
The initial expense of watercooling though is high.