I was down to the last 6GB on the 320GB hard drive in my iMac. I needed to replace the drive with a much larger one. After checking out the instructions for disassembling an iMac I thought it best to wait for Geoff to come home since he's a lot more comfortable doing this than I am. So I ordered a 1.5TB drive and waited. While I waited I judiciously selected which photos and videos to save and discarded those I felt were not worthy of taking up the last of my hard drive space.
Yesterday was the big day. Geoff handily took the system apart and swapped out the hard drive. It's the piece with the green circuit board. After putting it back together without having any extra pieces left over (amateur!), he booted up off the Mac OS CD, repartitioned the new drive, booted up again and told it to restore from the backup I had on the external drive.
About three hours later I was back online with tons of available bytes. Remember when a 100MB or even a 20MB drive seemed like an immense amount of space?