My first laptop was a G4 12" Powerbook. The battery never showed signs of weakness in the 3 years I owned it. I sold it to a friend who has owned it for 3 years now also. No need for a battery replacement. However the 15" G4 powerbook I bought in 2005 needed a battery in a year, but I sold it. The MacBook Pro I bought needed a battery with in 10 months so I bought one but the battery I purchased does not hold much better of a charge then the previous battery did. It starts out saying the life of the charge is 2.5 hours then 30 minutes later its down at 45 minutes. Quite annoying but what can you do? I think I'm going to get a Macbook Air later this year and sell my Macbook pro.