My Gateway (actually re-badged Samsung) Centrino notebook dims the screen to 25% when the AC cord is removed and restores it to 100% when AC is reconnected. However, I don't know how this is accomplished, as there is nothing in my Power options under the Control Panel to control it. At any rate, this is a very effective notifier and I quite miss it when I play around on my wife's Compaq, non-Centrino, notebook.