Good news. It's worked.
I was even able to change the HD access mode in BIOS back to "auto" afterwards.
I am currently on my PC with all my files and programs. I figure I'll use the old HD as backup until it dies.
There are still some small bugs to work out (*censored* is SCSI/RAID and why does it keep wanting to install? Disabled in device manager unless you guys think I need it.) but all problems seem miniscule compared to the other catastrophic failures and the amount of effort I've spent over the past week.