How do I upgrade from Exchange Server 5.5, Standard Edition, to Exchange Server 5.5, Enterprise Edition?

A. When you install Exchange 5.5/E on a functioning Exchange 5.5/S server, the setup routine detects that you're upgrading an existing server. Accordingly, the routine doesn't wipe out your existing databases; instead, it installs the new database code (as well as the additional connectors and other Exchange 5.5/E-only features) and upgrades the database files. Before upgrading, you should do full online and offline backups of your server.