I got the new drive installed and working. What was holding me up from returning the old one was that the old drive did manage to boot even though it continues to test with a bad sector. That being the case, I was uneasy sending it back loaded with so much of my personal data, so I had to spend some time erasing as much of the drive as I could, and that took a couple of evenings.

I have my personal data erased from the drive using one of the file-erasing tools. (I sort of wish I'd had a bulk magnet handy.) The old drive is now packed up in the return box and I'm going to drop it by the DHL office on my way to work this morning.