When you upgrade to Exchange Server 2007, you cannot perform an in-place server upgrade on an existing Exchange server. Instead, you must install a new Exchange 2007 server into the existing organization, and then move the required data to the new Exchange server. Exchange Server 2007 supports mixed environments that include Exchange 2000 Server, Exchange Server 2003, or both. This allows for an easier and more gradual transition. For more information about how to plan and deploy Exchange Server 2007