First of all how quiet does this need to be? I am extremely distracted by noise and my Intel Pentium III 866, that came with the retail HSF is very quiet. I have a fan on the video card (GeForce2 GTS), a rear 80mm fan exhausting, a front 80mm fan intaking air, and the fan on the CPU itself. This computer is quiet as HELL. Needless to say, I bought a nice case with a 300w power supply, and any time you buy a high quality case, more than likely the components (including the power supply) will be high quality and run quiet as well.
If you REALLY just want something DEADLY silent, this is what I recommend. Found at
this link you can find a company which focuses on quiet computer parts. They have a SilentDrive enclosure which is supposed to dampen and reduce the amount of noise coming from your hard drive, they specialize in ultra-quiet power supplies, their case fans are supposedly some of the quietest, or so their website claims, and they even have low noise coolers for Duron and Thunderbird processors.
If you honestly don't want to spend a lot of money customizing your system, then do yourself a favor and just pick up an Intel PIII processor retail kit. The fan that comes with the kit is very very quiet, and buy yourself say, a 700mhz chip, so you won't have to use any sort of intake or exhaust fans, so long as you have decent case ventilation. A larger case will help out with this. Also make sure you get yourself a video card which does not require a fan to be running on the chip, such as a GeForce MX.
divinemartyr