Battery Monitor is a simple program that will notify users about available Power Options in Laptop. But, this feature will be missing in few laptops making it very difficult to switch towards power efficient plans.
PowPlan is a free and light weight application that will make it easy to switch between different power plans. The app resides in taskbar making Power Management simpler and easier in Windows 7.
To reduce the brightnes all you have to do is left click on the PowPlan icon and Right Click will switch to different power plans.