I'm running os x on my PC (yes, you did read that right, check out the osx86 project) and that's much harder on my cpu than other os'es and my cpu fan was constantly going full tilt, it actually was in my other os'es too actually, I removed the fan, cleaned the heatsink and accidentally removed the heatsink from the cpu. What that was originally on there seamed fried, a bit like if you put a bit of toothpaste on a finger and rub it for a while. I cleaned that and put some decent stuff on there, I don't know what compound it is exactly bit it looked like a silverish putty and cammed from a Intel Xeon heatsink packaging. Ever since, my cpu fan hasn't even went faster than usual, even when running intensive audio sessions in garageband with tons of other applications open (my computer ain't a fast machine). I don't know if it's the cleaning of the heatsink or the putty that did a difference, but my ears are happy. If I was in your position, I'd probably buy some quality stuff as I found it made a huge difference in my computer. Not like it was a huge investment...