I ordered the Zalman CNPS7000-Cu (same thing only pure copper instead of copper/aluminum mix). I'm using it on a P4 2.4Ghz 533, and its the best thing I could find at a reasonable price. Cost me $43, I think the AlCu is a little bit cheaper. Anyways, I read that the Zalman CNPS7000 models are 20~25 db, so I would go with that if I was you. Unless of course you like your PC to be noisy