Its a good idea to stay current with you battery updates from Apple. The latest one, Battery Updater 1.4 improves the ability of Macbook batteries to maintain a charge when your computer is shut off for an extended period of time.
These are the models affected:
MacBook (13-inch), MacBook (13-inch Mid 2007), MacBook (13-inch Late 2006), MacBook (13-inch Late 2007), MacBook (13-inch, Early 2008), MacBook (13-inch, Early 2009), MacBook (13-inch, Late 2008)
Mac OSX 10.4.11
Mac OSX 10.5.6
Here is the link to download the update http://support.apple.com/kb/DL788
Here are some tips for taking care of your battery
These tips will apply to most all notebook computers with the lithium ion batteries.
Macbook, Macbook Pro, Macbook Air, PowerBook G4 (15-inch Double-Layer SD)
These batteries have an internal processor that keeps track of how much energy is in the battery. When you first purchase your computer or get a new battery it is best to calibrate it and then from time to time recalibrate it for optimal use.
If you keep your computer connected to its AC adapter most of the time and dont use it on battery power much, you should calibrate it about once a month. But keep in mind that never using your battery can shorten its life. In some cases, continuously charging a battery and never using it can wear it out in as little as a few months.
If the battery or computer isnt going to be used for a month or more it is best to remove
the battery. Be sure to recalibrate after you reinstall battery.
1.Charge your battery until the light ring or LED power adapter plug changes to green.
2.Allow the battery to cool for at least 2 hours. Its ok to use your computer during this time as long as you leave it plugged into the AC adapter.
3.Now unplug the AC adapter and allow the computer to run on battery. Again, its ok to use your computer as it runs the battery down. When the battery gets low a warning will appear on screen.
4.Now save your work and continue to use your computer. When it gets very low it will go to sleep.
5.Allow it to sleep or turn it off for 5 more hours.
6.Reconnect Ac adapter until its fully charged again.