I've had this computer since 2006. It started slowing down, and so I put more ram into it... a few years later, Applecare told me my hard drive was failing because it took so long to boot up. I wiped the computer, which got rid of many of the start up items, and sped it up... I upgraded the OS to Snow Leopard (which I immediately downgraded). Then I got the mouse fixed. By this time, the computer was slow, hot, the mouse was erratic, and programs took a long time to upgrade. My Windows 7 netbook would run better. Applecare just told me it was because my computer was old, and a new computer would fix my problems. Then I saw a post by someone on here, who said that he created a new user account and it made his powerbook run like new. I did that, rebuilt the driver cache, and guess what. My erratic mouse is no more, and my computer runs like new again! So let this just be a word of warning, OS X suffers from OS Rot just like any other OS, and sometimes a fresh install, without transferring your user account, but creating a new one, can really help speed up your computer.