Battery life is crucial on your laptop...without a doubt mine always goes dead when I am half way through a 3 hour flight. One of the biggest power drains on your laptop is the display brightness.
The display on a typical mobile PC consumes more battery power than any other part of the computer. Windows 7 automatically reduces display brightness after a period of inactivity, much like my BlackBerry does.
Even better, Windows 7 intelligently adapts to your activity. For example, if the screen dims after 30 seconds and you immediately move the mouse to brighten the display, Windows 7 will wait 60 seconds before dimming the display again.