Now that both Exchange 2007 SP1 and Windows Server 2008 are available, enterprises looking to transition from Exchange 2003 should begin planning the transition. Identify the number and specification of the servers required based on the number of mailboxes supported and whether the enterprise will use the Unified Messaging role. Then, follow the links to Microsoft's thorough strategy discussions and checklists.
Why Leave Exchange 2003?
Exchange 2007 offers a number of useful features. In particular, Exchange 2007 SP1's new geo-clustering option (Standby Continuous Replication) will help enterprises looking to replicate off-site. Additionally, the Exchange Storage Engine (ESE) operations are now optimized to use less memory and handle I/O more efficiently.