BatteryBar builds a better battery meter
Once you download and install BatteryBar, you'll need to right click on the Windows taskbar and add a new toolbar before it will show up. You should be greeted by a meter showing what percentage of your battery life is remaining. Left click on the icon and you'll get an estimate of how much operating time you can squeeze out of your battery.
And when you hover your mouse over the meter you get far more detailed information including the battery capacity and how long your battery should be able to run on a fully charged battery.
BatteryBar is available as a free download. You an also upgrade to BatteryBar Pro for $7.50. The paid version adds support for themes and changing active power schemes by right-clicking on the toolbar.