I did buy a new hard drive today and installed it. It wasn't quite as straightforward as the owner's manual of the computer made it out to be, but I still got the machine back up and running very easily. I'm amazed at how much easier it is to install a hard drive than it was 15 (or 20) years ago.
The old one was a 40 gig; the new one is 80. I don't think anyone even makes 40 gigs anymore. The system restore discs that came with computer worked perfectly snaglessly in getting the OS installed on the new drive.
It worked so well I think I might upgrade the RAM next. I might even upgrade the microprocessor if I get really brave.