PATA drive has that 50 pin connector that you saw. SATA has a much smaller pair of connectors (6 and 4 pin, I think) in one shell.
Maybe this is a good time for you to upgrade to an Archos 48 Android tablet, which comes with a 500gb SATA drive that can (maybe) be upgraded to 1TB, and is smaller than your jukebox, if you really need an ultra capacity portable. It's discontinued but there are still some left and I feel like grabbing one even though I don't really have a use for it, because I don't know of anything else being made with such capacity, and it's fairly cheap as such things go. It runs Android 1.6 (old, crufty) but the openaos.org folks have apparently ported cyanogenmod to it.