Are you thinking of upgrading to Windows Longhorn Server. This will give you an idea of what's involved in updating the domain and the forest in terms of the schema. If you have a domain with Windows 2000 Server or Windows Server 2003 with Active Directory installed on it, and are planning to install a Windows "Longhorn" Server domain controller to the network domain, you will need to update the schema on the current domain controllers before it'll work. If you are going to perform an unattended installation, you'll have to do this on the domain controllers before you actually install Windows "Longhorn" Server and Active Directory. You can do this by updating the schema on the domain controllers that either host the schema master or infrastructure master. If you are not going to install Windows "Longhorn" Server, please do not update the schema for the sake of it.(continue at source)
Are you thinking of upgrading to Windows Longhorn Server. This will give you an idea of what's involved in updating the domain and the forest in terms of the schema. If you have a domain with Windows 2000 Server or Windows Server 2003 with Active Directory installed on it, and are planning to install a Windows "Longhorn" Server domain controller to the network domain, you will need to update the schema on the current domain controllers before it'll work. If you are going to perform an unattended installation, you'll have to do this on the domain controllers before you actually install Windows "Longhorn" Server and Active Directory. You can do this by updating the schema on the domain controllers that either host the schema master or infrastructure master. If you are not going to install Windows "Longhorn" Server, please do not update the schema for the sake of it.(continue at source)