Ok
primero ve a
http://www.microsoft.com/windowsserver2003/evaluation/whyupgrade/win2k/w2ktows03-2.mspx y bajas el documento que aparece en la pagina arriba del lado derecho
Al abrirlo podrás ver que el nuevo AD soporta el cambiod e nombre e dominio a condición que todos los servidores DC del dominio estén en modo 2003 y no halla ningún server anterior.
"Domain rename. Rename any domain running Windows Server 2003 domain controllers. You can change the NetBIOS name or DNS name of any child, parent, tree- or forest-root domain."
Raising Domain Functional Levels
Once all domain controllers are running on Windows Server 2003, you can raise the Domain and Forest Functionality to Windows Server 2003 by opening Active Directory Domains and Trusts, right clicking the domain for which you want to raise functionality, and then clicking Raise Domain Functional Level.
Note that once you raise the domain functional level, domain controllers running earlier operating systems cannot be introduced into the domain. For example, if you raise the domain functional level to Windows Server 2003, domain controllers running Windows 2000 Server cannot be added to that domain.
Lee tambien
Upgrading Windows 2000 Domains to Windows Server 2003
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/windowsserver2003/proddocs/deployguide/adsec/part1/rkpdsw2k.aspHOW TO: Raise Domain and Forest Functional Levels in Windows Server 2003
http://support.microsoft.com/default.aspx?scid=kb;en-us;322692HOW TO: Rename a Windows 2003 Domain Controller
http://support.microsoft.com/default.aspx?scid=kb;en-us;814589Support WebCast: Windows Server 2003: Upgrading, Migrating, and Restructuring Windows Domains
http://support.microsoft.com/default.aspx?scid=kb;EN-US;329471mas info en
http://support.microsoft.com/default.aspx?scid=fh;EN-US;winsvr2003adEl GPMC es para las politicas nada mas y el otro es para mover objetos del AD mediante LDAP
Todo lo anterior te sirve en especifico si no cambiaras de equipo pero si lo harás,, lo mejor seria unir el nuevo equipo con 2003 al dominio, promoverlo a DC, transferir el FSMo y después ejecutar todo lo que puse anteriormente