For a good CPU fan/heatsink combo, I would go with the Vantec Tornado mounted on a Thermalright SLK948U. The heatsink is compatible with Socket 939, Socket 940, Socket 768, and Intel's Socket 478, giving it much flexibility, in addition to having a huge thermal conductivity. The Vantec Tornado is a monster, moving the most air that I've ever seen in an 80mm fan.
There is one problem, the Vantec Fan is rather loud, so whilst you are not gaming or running on high load, you may want to invest in a Pentiometer set so you can slow the fan down.
Athlon XP 2000+ @ 2.1 GHz
Corsair TwinX 1 GB Matched @ 2-5-2-2 clocks (took me a while to get that!)
Gigabyte VIA KT400 Ultra+ (SATA Model)
2x80 GB Western Caviar SATA @ RAID 0
Plextor DVD+/-RW 12x (712A)
Norcent 52x32x52x CD-RW
2x Pioneer DVD +/-RW 8x
8 USB 2.0, 4x Firewire 400