Your company has a Windows Server 2003 Active Directory forest that contains a single domain. The functional level of the forest is set to Windows 2000 native.
You have an Exchange organization that contains Exchange Server 2003 Service Pack 2 (SP2) and Exchange Server 2007 Service Pack 2 (SP2) servers.
You plan to transition the organization to Exchange Server 2010.
You need to prepare Active Directory for the installation of the first Exchange Server 2010 server.
What should you do()?