Hello, I am in the process of transitioning from Exchange 2003 SP2 to Exchange 2010 SP1. There is a hollow root AD domain, and all user AD accounts and Exchange servers live in a child domain. My question is will the GUI setup run all the necessary parameters for this scenario, or do I still need to run setup /PrepareAllDomains and setup /PrepareLegacyExchangePermissions from an CMD prompt? I am using an account that is a member of Schema Admins and Enterprise Admins.

Yes, if you do not run cmdlet individually then it will run all reqired step when you run. The advantages of running each step separately are that you can run each step with an account that has the minimum permissions required for that step, and you can verify completion, success, and replication before continuing to the next step. So in your case you can proceed with setup /PrepareAllDomains. Have a close look of below KB in detail and then proceed. Prepare Active Directory and Domains:: http://technet.microsoft.com/en-us/library/bb125224.aspx Anil