To cut a long story short: I had 2 disks to test, one a Seagate and the other a Samsung.
Using Seagate’s diagnostics utility SeaTools was a very smooth experience. After booting from the CD, a GUI application automatically started, including mouse support. Even basic users would feel right at home.
Trying to get Samsung’s HUtil to work was a nightmare. Apparantly Samsung are as of yet unaware of the existence of SATA CD/DVD-drives. Using the CD my PC booted into FreeDOS just fine, but their script couldn’t detect the CD-drive so it couldn’t start the diagnostics utility. Trying it manually failed too because the included drivers simply don’t support SATA drives.
I spent half an hour going back and forth changing settings in the BIOS and rebooting to no avail. This worked for some people though, so ymmv. Check out any settings on SATA compatibility modes.
One post on the internet revealed a method of booting using the Ultimate Boot CD, then switching to Samsung’s CD, and running the diagnostics from there. After reading up on UBCD, turns out those last two steps aren’t even necessary. UBCD includes the latest diagnostics utility for any hard-drive out there! Just boot it, select the utility from the menu, and it automatically starts.
So if you ever need to do a diagnostics on a disk, don’t bother downloading and trying to boot the manufacturer’s utility. Just pop in the UBCD and you’re off. It also includes other stuff to do just about anything with your computer. Neat!