Terminal Server

Hi

I have a windows 2008 server setup with Terminal services, I have created remoteapps icons for clients that works great. however when the open the RDC icon (not the remoteapp icon created) the IP address is cached and they can log on directly to the server desktop getting access to other programs.. not good.

is there a way to disable them from loggin on to the desktop.. all i want is for them to have remoteapps to one application only.

Thanks,
Server newbie..