I recommend a Thermaltake Volcano 5 (or if you can't find one, a Volcano 6CU, or a 6CU+ with a fan speed controller). Usually in the range of $12 or so, and the fan on it is nice and quiet while keeping the CPU temp around 105F idle / 115F full load (on an XP2000+ of mine). If you want a different brand of HSF, I'd recommend looking for one with a fan in the 4500-5000RPM range, because they tend to produce less noise than the 7KRPM while providing more-than-adequate cooling for a non-overclocked machine.