By now, you're probably aware that Exchange 2007 is a 64-bit only product, at least in production. However, before you take the plunge to transition to Exchange 2007, make sure you're aware of the organizational requirements that must be met.
- Your Active Directory domain must be running at a level of Windows 2000 native or higher. If possible, use a level of Windows Server 2003.
- Your Active Directory forest must be running at the Windows 2000 functional mode.
- If you require forest-to-forest trusts, your forest functional level must be Windows Server 2003.
- Your legacy Exchange organization must be running in native mode. This means that you can have no Exchange 5.5 servers in the organization.
- Any legacy Exchange servers must be running Exchange 2003 SP2 or Exchange 2000 SP3.
- The domain controller running the schema master FSMO role must be running Windows Server 2003 SP1, Windows Server 2003 R2 or higher. The same holds true for servers running as global catalogs.
For minimal potential problems, eliminate any Windows 2000-based domain controllers from the environment by upgrading them to Windows Server 2003. Although not required, this step simply makes life a little easier.