I have a 2009 MBP which is in a pretty good condition. I've just upgraded it to Mavericks. Now, the issue that remains, along with the possibility of upgrading the 4GB RAM, is the battery which only lasts about 2 hours (according to the calculator). I would like a genuine battery - can't be trusting any Chinese replacements here. The thing is would it be worth upgrading to get a larger capacity? Battery life is important for me, but I don't know what the original battery capacity was to know if it'd be an improvement worth going for? *Also how do I know what model of battery I need?