I've been running Exchange 2010 for about a year now. When we did the upgrade we stood up a new domain, created domain trusts and migrated the 2003 mailboxes to the new domain based exchange 2010 on a physical server (it is the DC role as well) and linked the mailboxes back to the main security domain. It has worked well but it is has that extra administrative overhead we would like to remove as we are a small company with just two IT people. Plus having a domain of just one computer that is exchange and DC scares me from a resiliency standpoint. I am looking at setting up a two DAG Exchange 2010 in my main security domain using Kemp loadbalancers. These 2 Exchange servers would be on HyperV deployed 2008R2 Enterprise VM. Once I transfer the boxes, manually recreate the forms, and reroute to the new servers I will be simply removing the old domain trusts uninstalling exchange dcpromo down the dc in the now unused domain. This old physical server will then become a HyperV host. We have not had messaging in the security domain and i thought I had cleaned up everything related to the old 2003 exchange right after I moved to the new setup but I am seeing many exchange entries still in ADSI. My question is what steps do I need to take to ensure that I have a clean AD for the 2010 install on the security domain. Can I just install the new Exchange 2010 and start testing and it will take care of Schema updates, everything I have found on this topic assumes you are going to be running a mixed messaging environment.