Followup: Tech curse
Well I’m a happy camper now, at least where hard drives and firmware is concerned. Turns out it was a problem with the specific version of the Oxford 911 chipset I had in the external case I was trying to use. I swapped cases with a newer one from work (also Oxford 911 based) and the new drive worked fine.
Last night was a file-copying night, and I now have all my music on the new 200gb drive, all video stuff onto the 120gb drive, and all are working fine. Better than before actually, since the work enclosure is smaller and more portable, as well as having a smaller quieter fan that turns off when the drive isn’t spinning. So I don’t have to sleep with the noise of a hard drive anymore.