Hi Farhan, The migration from Exchange 2000 to Exchange 2003 is the easiest.. I would recommend that you do the move mailbox method. Where in you install Exchange and joing the exisitng site. Once that is done use the Exchange system manger to move the mailobxes to the new e2k3...right click the mailobx>select exchange task>move mailbox>select the new server and store. IMP:installing exchange on a domain controller is a no no.