Are there any Active Directory design constraints in Windows SBS 2003 R2?
Yes. Windows SBS 2003 R2 has the following design constraints: only one server in a domain can be running Windows SBS 2003 R2; it must be the root of the Active Directory forest; you cannot create trust relationships with any other domains; and an Windows SBS 2003 R2 domain cannot have any child domains. In addition, all the flexible single master operations (FSMO) are restricted to running on the Windows SBS 2003 R2 server.