Q: I am using Windows Vista, and somehow my battery meter (in the tray/notification area) that indicates battery/AC, and let me switch power schemes, is GONE! How do you turn it back on?

A: Usually, you just turn it back on by right-click the taskbar, go into Properties, and in the "notification" tab, you make sure the "power" choice is checked.

However, in some cases, that is grayed out. Usually, that means something had disabled it. Try the following steps (warning: this involves messing with the registry!)

http://support.microsoft.com/kb/945011

On the other hand, I've found an excellent alternative app that shows much more info about your battery, power, and system info. It's called BattStat