if you don't absolutely need to upgrade the internal drive, you can get much more space and better performance out of a 3.5" desktop drive in an external enclosure. granted, these are bigger and require external power sources, but if you plan to do video editing or something that requires lots of space, this is probably your best bet. (especially since most people will tell you that having the application and video on separate hard drives is advantageous). if you do this, your best bet is to buy an empty firewire enclosure ($50-$60) and then buy a separate drive to put in it, as this usually costs a lot less than the external hard drives sold by Western Digital, Maxtor, etc.. for less than the cost of an 80GB laptop drive to put in your TiBook, you can get an external enclosure and a 200GB desktop drive from Western Digital or Maxtor.