I recently had to change out the hard drive on my partner's iBook G4. It's a tremendously difficult procedure with (what seemed like) over a hundred screws that need to get removed in the proper order. iFixit has a great guide series for disassembling and reassembling your Macs and iPods, including a very useful screw reminder sheet that I used to cellotape all the screws to in the order that I removed them: http://www.ifixit.com/Guide/
I put the old drive in a portable USB enclosure and used SuperDuper! to clone the old drive to the new one. Everything worked spankingly and my partner now has a 100 gb drive to put her huge iPhoto database on! And an external 60 gb USB drive for backups.
You'll need an assortment of teeny Phillips screwdrivers (including a Torx, although I used a hex driver) and a "spudger" or a little lever tool that helps you crack the iBook case. iFixit will sell you one, I used one that I had from my camera repair toolkit. A small set of tweezers was also great for picking up small parts. My screwdrivers are magnetized, which also helps with the small screws.
p.s. I wish Apple made the iBook easier to maintain! You shouldn't have to take out 100+ screws just to change out the hard drive!
