We've set up part of our Active Directory (AD) environment. In the process, one of our overzealous administrators performed an Exchange 2000 Server ForestPrep. Because our migration was postponed, I used the instructions in the Microsoft article "XADM: How to Completely Remove Exchange 2000 from Active Directory" (http://support.microsoft.com/?kbid=273478) to clean things up in AD. What will happen when we start our real migration?
The schema updates you made are still present in AD--you can't remove them without restoring the directory to a previous revision. Remember that ForestPrep makes the schema updates, but it also creates placeholder objects in AD, and you deleted those objects when you followed the instructions in the Microsoft article to use the Update command with the /removeorg switch. When you do an Exchange Server 2003 ForestPrep, you'll get the new Exchange 2003—specific schema extensions and a new set of Exchange organization objects.