I bought my 12" PowerBook G4 in Jan '04 and I love it. I thought the 40GB HD would be enough. But now that I'm down to almost 20BG (in just 3 months), I'm thinking an upgrade might be in order. Can anyone provide advice on the best way to do this, and if there is the possibility of it causing problems in the future? I'm looking to keep my PowerBook for a long time, so I don't want to screw it up. Thanks!