MS: How to lock down a Windows Server 2003 or Windows 2000 Terminal Server session

You can use Group Policies to lock down a Terminal Server session on a Microsoft Windows Server 2003-based or Microsoft Windows 2000-based computer. With the following settings, even the administrator account will have restricted access. It is highly recommended that you create a new organizational unit instead of modifying the policies on an existing one.

http://support.microsoft.com/kb/278295