macbook 13-inch, Aluminum, Late 2008 battery problem

hey guys i have a macbook 13-inch, Aluminum, Late 2008 and it is having a problem with holding a long charge and able to use it for more than 2 in a half hours. i am thinking of getting a new battery but was wondering if a 3rd party battery is better.

need some input. the programs i mainly use on this computer are:

Google + (hangouts)

BBedit 10

Pixelmator

Safari

Google Chrome

Firefox

Spotify

Operating System: Lion 10.7

if someone can help me that would be awesome. thank you guys and "Stay young, Stay Hungry"