lammert - 8:00 am on Apr 26, 2011 (gmt 0)
SSH is a protocol which allows to to login to a text command prompt on one of the remote servers. This allows you to start commands directly on that server. If your desktop is not Linux based, you will need a terminal emulation prgram to create that connection.
On the remote server you can use the SFTP command to transfer files from one server to the other. SFTP is a command line tool which allows you send files from one of the servers to another.