CodePlex hosts a very handy Windows Vista Battery Saver utility. This utility automatically deactivates certain features of Windows Visa, such as the Aero User Interface and Sidebar, and changes the power plan when switching to battery power.
After AC power is restored, the utility reactivates the desired features and resets the power plan. A nice utility written by Tamir Khason, that could – according to the website of the utility – save you up to 70% of battery power.
Windows Vista Battery Saver, Freeware, Software, Download