Here are some tips to make your laptop last longer:
Dim your screen - Most laptops come with the ability to dim your laptop screen. Some even come with ways to modify CPU and cooling performance. Cut them down to the lowest level you can tolerate to squeeze out some extra battery juice.
Cut down external devices - USB devices (including your mouse) & WiFi drain down your laptop battery. Remove or shut them down when not in use. It goes without saying that charging other devices (like your iPod) with your laptop when on battery is a surefire way of quickly wiping out the charge on your laptop battery.
Run off a hard drive rather than CD/DVD - As power consuming as hard drives are, CD and DVD drives are worse. Even having one in the drive can be power consuming. They spin, taking power, even when they?re not actively being used. Wherever possible, try to run on virtual drives using programs like Alcohol 120% rather than optical ones.
I would like to highlight the last point. I see a lot of people watching anime from CDs when they could in fact just copy it over to the harddisk. It saves that bit of electricity to let you watch an extra episode of your Ouran Host Club anime. So do take note. 
Finally, if you’re not using your laptop, just switch it off, the screensaver doesn’t help much. Using a laptop to listen to MP3 is a complete waste of electricity too. Be a little more energy saver, borrow a book from a library or just listen songs through a music player.
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I’ve found that using virtual drives over the actual CD drive saves up a lot of power!
by Mike (Oct 1, 2007 at 7 PM)alcohol of daemon tools are the two choices i would choose.