I bought a refurbished ibook G4 just four months ago and the harddrive has taken a dive. The certified dealer I bought it from has quoted me a $350 price tag to install a new harddrive. It seems like a lot--but I know little about it and he is the only dealer within an hour's drive. In the past, I've kind of felt a bit taken advantage of with this guy, so I'm wondering if there are other options. Is it possible to buy a harddrive and replace it myself? Or is that begging for trouble?