Thank you for the fast assistance.
acid_kewpie: Yes, that makes sense -- I need an SSL connection, not SSH. I will test stunnel ... need to read up on it a bit to get it configured correctly.
uteck: rdesktop -E would not connect.
I have located other requests, on the web, for a linux remote desktop client that is equivalent to the updated RDP 5.2 client for XP, capable of connecting to Windows servers that use TLS/SSL server authentication. (see http://ubuntuforums.org/archive/index.php/t-310813.html
) It seems that rdesktop in itself does not include TLS/SSL support.
HOBlink jwt for Linux may be a possibility.