Completing Post-Upgrade Tasks
After upgrading the operating system on all domain controllers in the forest to Windows Server 2003, complete the domain upgrade by raising the domain and forest functional levels to Windows Server 2003, and use newly created application directory partitions to store DNS information. You must then redirect the Users and Computers containers.
Figure 9.8 shows the tasks necessary to complete your upgrade to Windows Server 2003 Active Directory.
Figure 9.8 Completing the Upgrade to Windows Server 2003 Active Directory