Thanks, MisterMe.
I installed a new hard drive on my own clamshell ibook a couple of years ago. It's a pretty complicated operation, and I'm reluctant to take hers apart, in case something should go wrong. She has another computer, a nice Imac DV, which I'm getting back up to speed for her with new memory and a new OS. That will be her main one, and the ibook will be just for portable uses.
I agree with you about the new hard drive, though. It doesn't just give you more storage, but also makes the system run faster. It's like having a new computer.