When preparing an existing Active Directory environment for migration to Windows Essential Business Server one must run a tool which scan the environment and make sure that no errors exist before the migration can even start. This tool is called Windows Essential Business Server Preparation and Planning Wizards and can be downloaded from Microsoft Download Center without cost.
The thing is that this tool is a great utility to use in existing environments, even though they are not being migrated and never will be migrated to Windows EBs. The tool is a great health check and will most likely show errors or potential problems you had no idea existed in your server environment. It find problems with DNS, in Active Directory and replication and will guide you to recommended system changes and much more. I strongly recommend everyone to run it on your own environments to see what it finds.
Just a quick note related to scanning for errors and best practices is that the upcoming Windows Server 2008 R2 will include a number of best practices analyzers for roles such as DNS, Active Directory and many more. This is really slick!
Download Windows Essential Business Server Preparation and Planning Wizards