Howdy cso.dave,
Agree with Bdude. As many fans as your case allows you should use. And when purchasing a new heat sink fan for your
CPU you should always check for comparability ex.. socket 939 754 etc.. If it was not for a heat sink and fan for your
CPU it would die within a week maybe even sooner.
I also suggest heat sinks for your
ram as well. You'll get the most life out of all your products if you just buy some heat spreaders and heat sinks etc, and there not to expensive.
As for the noisy part some of them can be louder than a vacuum, but some of them are quite this is why some people get fan controllers to turn then fans up when your doing intensive PC work and turn them down when your not.
Let us know what socket you have we can point you in the right direction.