oh and for those of you who keep killing the battery life, follow these rules:
once the battery is done charging, unplug the AC adapter. if you keep recharging the battery, it's gonna wear down the battery and lose its charge capacity. i see too many people doing this with their laptops. they leave it plugged 24/7 and wonder why their battery life sucks. if you want to plug it in all the time, then remove the battery. you're only killing your battery's life.
don't charge the battery before you need to. try to use up all the battery power to the point where you're prompted by the OS to recharge it. if you keep recharging the battery after minimal usage, it will use up a charge cycle. all rechargeable batteries have a limited # of charge cycles, once they are used up, they're gone.
and try calibrating/conditioning the battery once in a while. this means fully charge, then fully empty the battery, then repeat it once. it will condition the battery to reach and remember its minimum and maximum charge capacity.
change some settings to increase better battery life. remove any cd/dvd in your drive, turn down brightness, use power save modes on things you are able to.
if you're battery is no good, it might be best just to buy a new one and start using it keeping in mind not to do what i mentioned above.
and when buying laptop, never trust the battery life as advertised. it's always much worse than advertised.