Battery life, do i need a new one?

Your battery is aging normally. Its capacity will continue to gradually decrease. Normally batteries don't simply stop working, they just lose too much capacity to continue to be useful. So you know better than I do when it's time to get a new battery. You will get roughly 3x as much use out of a brand new battery than you do with your current one.

What do you use your computer for and do you need it to last a long time unplugged? The battery will continue to work (it won't just fail like a hard drive) but also continue to lose capacity.