So, I went and bought a new hard drive at Moondog Computers (which cost me almost twice what it would have online, but I wanted the drive now, and I wanted to support locally owned business). I already had an old external 2.5" drive enclosure, so I connected the old drive there, made a bootable thumbdrive of Clonezilla, and tried to clone the old drive to the new drive. I was seeing lots of I/O errors while running Clonezilla (which is Debian based), so I decided to try and freeze the drive.
Currently trying to clone the drive, but still seeing all kinds of errors while doing so. I'm going to let Clonezilla run for a few hours, and see if it makes any progress, but realistically, I think my HDD is shot, and I'm going to have to build the system up from scratch - let's hope I can find the relevant CDs and things.
My old laptop also had a hard drive that failed, and the replacement died on me as well. I've also had work computer HDDs crap out on me (in fact, my last work laptop had an HDD that was slowly dying, and had been replaced maybe a month ago).
You would think all this experience would teach me to have backups . . . *sighs*