I've got one on my Pentium D 820 (running at 3.5GHz) and it works pretty well. Temperature stay below 70deg C when both cores are 80%+ during video rendering (90minutes+) with the fan speed at minimum. It's pretty quiet at that speed.
However, with the fan set to maximum it's LOUD, very LOUD, and that's the setting need to out perform the Zalman 9500. The 9500 would probably be the better buy (the two seem similarly priced) because it seems to operate quieter with reasonable fan settings.
Checkout frostytech.com for some benchmarks on both.