ok, so I'm no expert on OS X (yet) as a new switcher, but it seems that if my 1.83Ghz MacBook idles at 1.5Ghz no matter I set the Energy Saver to, then maybe Apple has not yet written the power management control software to properly throttle the Core Duo chip. I do not have a comparable PC (only a 1.66Ghz Core Duo that idles at 998Mhz, but I welcome any feedback from others more knowledgeable who can educate me.