Just found this article on the 'Support policy for Exchange Server 2003 running on hardware virtualization software'....
"Microsoft supports Exchange Server 2003 running on hardware virtualization software (virtual machines) only when all the following conditions are true:
- The hardware virtualization operating system is Virtual Server 2005 R2 or a later version.
- The version of Exchange Server that is running on the virtual machine is Microsoft Exchange Server 2003 Service Pack 2 (SP2) or a later version.
- The Microsoft Virtual Server 2005 R2 Virtual Machine Additions are installed on the guest operating system.
- Exchange Server 2003 is configured as a stand-alone server, not as part of a Windows cluster.
- The SCSI driver that is installed on the guest operating system is the Microsoft Virtual Machine PCI SCSI Controller driver.
- The virtual hard disk Undo feature is not enabled."
Companies deploying Exchange 2007 sometimes require E2K3 servers in the organisation, in order to provide support for legacy connectors for example. It is an option to virtualize the E2K3 server in order to provide a bit more flexibility and to maximise the use of the available kit. Personally I think the decision to virtualize should be a strategic IT decision because it does add a layer of complexity and requires additional skills to support but definitely worth thinking about... And now that the support stance appears to have been revised the decision in an easier one, particularly for companies which have virtualized other areas of their environment.