Agreed, Wombat. My concern is, and I had this happen with 480GB of 24/96 files and ISO rips of 80 SACDs accidently get deleted because my daughter saved a filed in a folder and tried to fix it. Told my daughter, NO big deal, I have it on my ext drive. This from 2008 and it's 2011 and my back-up was a 500 GB Seagate drive. Well, I plug in the Seagate to my iMac...and the iMac won't read it. Spent hours and gave up. Tried plugging into company laptop with MS, no read again. I still have it and when I have the time I'll keep trying.
Sometimes it's the USB interface on those old Seagate external drives that fails. It may be possible to remove the drive from the enclosure, put it inside your PC (or inside an external drive dock), and recover the data.