This article shows us how to improve the security for Remote Desktop Protocol. “You can connect to a remote computer that is running Microsoft Windows Terminal Services by using a Remote Desktop Protocol connection. This kind of connection provides encryption for the data that is sent between the terminal server and the client computer.
However, this kind of connection does not provide authentication for the terminal server. You may want to make sure that your terminal server is correctly authenticated before you connect to it. To do this, configure your terminal server to use Transport Layer Security (TLS) to authenticate the terminal server and to encrypt the data that is sent between the terminal server and the client computer.”
For this to work, both client and server needs to be windows 2003 and patched with SP1.