Battery Alarm

Battery Alarm is simple Windows Vista program that will monitor your battery life and alert you when you are getting low on power.

All settings are customizable so it will notify you when you want and how often you want to be notified. You can also select the sound of the alarm. It is also very easy to install, since you just download the zip file and extract it. Then run setup.exe (If you manually installed an older version please manually remove it). It seems to work in Windows 7 as well and it is completely free.