Run the new versions of ForestPrep and DomainPrep when upgrading from Exchange 2000 to Exchange Server 2003.
Exchange 2000 Server cannot run on Windows Server 2003.
Remove the following Exchange 2000 Server components before upgrade: instant messaging, Exchange Chat, Exchange 2000 Conferencing Server, Key Management, cc: Mail connector, and MS Mail connector.
Upgrade front-end servers before back-end servers.
To migrate from an old Exchange 2000 Server organization to a new Exchange Server 2003 organization, use the ADMT in conjunction with the Exchange Server Migration Wizard.