You don't need to go watercooling - that's just for keeping your components cooler than having the equivalent noise of an air cooling.
A Zalman Super Flower HERE
or a Arctic Cooling Freezer 64 Pro HERE
for the CPU
An Arctic Cooling Silencer HERE
or a Zalman Super Flower GPU cooler HERE
For case fans:
Akasa fans, they do two series: Black Ultra Quiet and Amber, and their both silent.
Vantec Stealth fans are also very quiet.
For quiet hard drive: Samsung SpinPoint P120S, or one of the Western Digital Caviar drives
If you want a quiet PC, I would recommend going Socket 939, as the cooling solutions are much more developed.