I have a G4 PowerBook - the last model they released before switching to Intel chips. At the time I got the custom option of 7200RPM 100gb hard disc, but as this is my only computer I find that the space fills up quickly. I am using an external hard disc for all my iTunes content, but I travel between my home at University, and my parents' house a lot, and it's frustrating not having some things with me all the time. So I'm looking at the possibility of upgrading the hard disc. I found this and was wondering if this is compatible with my PowerBook? Also, will I notice a significant difference in speed between the current 7200RPM drive, and the 5400RPM one listed there? If there are any other recommendations for hard discs to put in, I would really like to hear them. Thanks!