iBook G4 opening procedure (for hard disk replacement)
Yes, it's necessary. Apple's designs aren't simple, and you need to keep track of the screws and which one fits in which position. Some of the screws feed into other components on the other side. Taking the bottom off is the easiest part! I once had a unit in where someone turned their computer over to "their next door neighbor, who knows all about computers." After he was done, they couldn't get a disk to load in the optical drive. I took it apart and he put a long screw in the wrong place and drove it right through the optical drive.

This might sound stupid, but you might want to print out each page where he's taking screws out, and when you take them out, use masking tape to tape them onto the position in the diagram they came out of. If you're not used to working on these units, it's very easy to put the wrong screw in the wrong place and either end up with a part that's not secured or driving the screw right through something else.

If you think an iBook is complicated, try replacing the optical drive on a 12" PowerBook G4 sometime. :-o

Hope this helps.