Support policy for Exchange Server 2003 running on hardware virtualization software cf http://www.support.microsoft.com/kb/320220
Microsoft supports Exchange Server 2003 running on hardware virtualization software (virtual machines) only when all the following conditions are true:
When you plan to deploy Exchange Server 2003 SP2 in a virtualized environment, the same performance and scalability aspects that are described in the "Exchange Server 2003 Performance and Scalability Guide" apply when you size each virtual machine for Exchange Server 2003.However, there are some factors that directly affect the performance and scalability of Exchange Server 2003 when Exchange Server 2003 is running on Virtual Server 2005 R2. These factors should be considered when you size both the host configurations and the guest configurations.
Microsoft has a general support policy for running Microsoft software in non-Microsoft hardware virtualization software. The policy that is described in the following Microsoft Knowledge Base article also applies to any version of Exchange Server that is running in non-Microsoft hardware virtualization software:
For more information about the Microsoft Virtual Server support policy, click the following article number to view the article in the Microsoft Knowledge Base: