hum; MS filesystem encryption is LOGIN specific, which is why I went to
FileAssurity OpenPGP (google for it). You create a PASS PHRASE
and then use it to decrypt (login once, decrypt many).
It will encrypt specific files, but the software would need to be installed
on every system to which you move the HD. the installer could be on the
drive, but it's just more admin (and licenses) to acquire.
I have managed to move the keystore to my thumb drive and to restore it
for future use; just haven't tried it on another system.