Under C.P.D.

>Esta migración no es la más recomendable mas aún una vez aparecido EBS 2008, prueba de ello es que no encontrareis ninguna guía oficial que os ayude a realizarla, de todas formas, cabe destacar los pasos seguidos por un participante en los foros de MS. los cuales parece ser que han terminado satisfactoriamente y ha conseguido realizar una migración para 73 usuarios en 4 horas, Exchange, buzones y carpetas públicas incluidas, los pasos son estos:

microsoft.public.windows.server.sbs

1. Add the new 2008 server as a member server in the existing SBS 2003 domain.
2. Run adprep on the SBS to update the AD schema.
3. Add Domain Controller to current domain
4. Add Exchange server to the current domain.
5. Add Security Server to current domain
6. Promote 2008 DC to domain controller in current domain.
7. Install .NET 1.0
8. Install ExPRA
9. Run Exchange best practices analyzer
10. ServerManagerCmd -i powershell
11. ServerManagerCmd -i RSAT-ADDS
12. Install IIS, and compatibility add-ons for new exchange server
13. Transition mailboxes to the new server.
14. Transition FSMO roles from SBS 2003 to 2008 server including naming master
15. Redirect Inbound Mail to the Exchange 2007 server
16. Move public folders the Exchange 2007 server
17. Migrate DNS server
18. Finalize Exchange Server Migration
19. Move a CA to a Different Computer
20. Change login scripts
21. Move group policies etc. to 2008 server.
22. Change the domain controller that Exchange 2007 connects to
23. Remove SBS 2003 server from domain.

Joe Capuano.