So I bought my PowerBook G4 brand new in 2005 pre-loaded with 10.3 Panther. At that time the PowerBook felt like a real snappy and great laptop. However, by the time I upgraded to Leopard, the computer felt so slow even at things such as web browsing or using Mail.app. So my question is, how long do you think (how many OS revisions) our MBPs will last before we notice a significant decrease in performance?