4. Laptop Linux

Linux doesn't have as many built-in power management options as Windows. You can switch it into laptop mode to concentrate disk activity into short stretches of time, however, with up to ten minutes between accesses. There's a list of tools to enable laptop mode at www.samwel.tk/laptop_mode/tools/. Powersave and Powermgr (both on sourceforge.net) give you power profiles including CPU speed, screen brightness, Wi-Fi, services and other settings that affect battery life.

Stay Up To Date

Some BIOS updates include improvements to power management. Windows Update and Apple's Software Update sometimes have patches that improve battery performance (or fix problems like the USB 2 power leak).

Defragment your hard drive regularly. The more efficiently files are stored on your hard drive, the less often the hard drive will need to spin up to find the next section of the file.

Adding more memory to your laptop saves power by reducing Windows' reliance on the virtual memory swap file on your hard disk. In Vista, plugging in a USB memory stick that you can use for ReadyBoost (supplementing system memory) can give you longer battery life - we've seen up to 15-20 minutes longer life on a Toshiba tablet PC using a 2 GB USB stick.

Charge Often

Another option is to get an extended battery for your laptop; for under $200 you can double or triple battery life. The more cells and the higher the milliamp hour (mAh) rating, the longer the battery will last; standard laptop batteries often have two cells, but extended batteries can have six, eight, nine or even twelve cells. The extended battery may replace the standard battery, or it may attach underneath the laptop, giving you better battery life (and a better typing angle as well!)

Look for a smaller charger, too; Kensington and Targus make smaller, lighter power adapters for many notebooks. You can also get adapters that charge your mobile phone or PDA at the same time, and connectors to charge in the car and in airplanes. Remember to keep an eye out for power sockets in airports and meeting rooms as you travel.