Don't forget that, if you are virtualizing a heavy I/O server like Exchange or SQL, the conversion process will quiesce I/O on the source while it is running. For extremely heavy I/O servers, this could potentially cause data loss so it is recommended as a precaution that the conversion occur during a user outage. If it is an MS Exchange server, shut down services on the physical source before converting (or use the cold clone CD but this may be complicating things)