Yes - it's possible to upgrade your iBook hard drive. I believe that it just uses a standard 2.5" (9.5mm high) notebook hard drive (like the PowerBooks and many PC notebooks). Unfortuantely, though, the HD replacement procedure for the iceBooks is very technical, so you'll probably want to pay the installation fee to have a professional do it for you, unless you feel that you're extremely qualified.. ;-) good luck!