I started using it about 3 months ago and think it is great. It cuts your CPU temperature by about 10-15 degrees when it's not doing anything. Obvioulsy it isn't much good when you are using CPU intensive stuff but when you are browsing the net and stuff most the time it isn't doing anything.

Without any case fans in my pc it keeps the cpu at about 36c most of the time which isn't too bad. Before it was about 50c which probably wasn't doing it any good. Other hardware stays cooler too as there isn't as much heat in the case. I only have a fan inside the case blowing directly at the HDDs just to keep the air moving and they stay about 30-32c which again isn't too bad. Could be better I know.

You can find it here - http://www.cpuidle.de

I'm using "CrystalCPUID" (http://www.silentpcreview.com/article231-page1.html) (it's free!) which probably works on the same (or similar) principle. With this fabulous software and undervolted fans and an enclosed HDD, I run my pc almost inaudibly. :cool: CPU temperature is 38c now while I'm editting with dictionaries and a browser on. I think it's a bit higher but no wonder at this hot night.

Recently got an Athlon 64 and with Cool n Quiet enabled it runs amazingly cool. Apart from last week with all the sunshine it's been staying around the 30 deg mark.