I'm running a P4 3.06 ghz 533FBS CPU. I use a Cooler Master fan/
heat sink combo. It's the twenty dollar one. Temps are consistently
38C- 45C depending on room temp. I'm told by a good source that you needn't worry until you hit 50C. My rig is a micro atx with raid 0. My next step is a new power supply with multiple fans.