When you create users or groups on a Windows Server 2008 SBS computer with Active Directory Users & Computers (dsa.msc), you wont see the users in the Windows SBS Console.

To fix this problem you'll need to open ADSI Edit and browse to the user or group and open the properties. In the Attribute Editor find the value msSBSCreationState and set it to Created, be sure to capitalize the "C" of Created. Now press OK and refresh the view of the Windows SBS Console.

Microsoft have also a tool available for download Windows SBS 2008 Active Directory Group Converter.

Note: For groups you also must set the group to Universal to make them available in the Windows SBS Console.