Why does Microsoft not allow me to use Terminal Services in application sharing mode on Windows SBS 2003 R2, as you could with Small Business Server 2000?
There is a security risk involved in running Terminal Services in application sharing mode on a domain controller. Since SBS is always a domain controller, we have disabled this functionality so to improve the security of our customers’ networks. If you have a hardware constraint, there is a whitepaper that explains how to run Windows Server with Terminal Services from within a Virtual Server on your SBS machine.