another thing. many people say that the best way to get your battery life up is to let it run all the way dead. THIS IS NOT TRUE!!! this will screw up the battery and make it not hold a charge for as long
Actually, totally discharging the battery every once in a while IS good for it.
The batteries build up a "memory", which means if you don't totally discharge them every so often, the battery charges from the "memory" point instead of dead empty, shortening its potential charge. I driven enough electric forklifts over the years to learn this very well. Plus, check your documentation with your lappys... all says the same thing.