You might also check to see in System Pref's if your processor performance is set to Highest, or Automatic. A setting of Automatic usually makes the computer work too hard for itself and thus creates noise. This can be checked in Energy Settings under System Prefs. When my iBook is set to Automatic performance, the fan is constantly on and the surface below the monitor gets extremely hot, but when set to highest or reduced, the fan only comes on once in a while and the computer is no where near as hot.