I have a single domain runing on Windows 2000 Servers and a Exchange 2003 server. There are two domain controllers, one holds all of the FSMO roles - and the other one is just there for redundancy. We just purchase a couple of new servers and I'd like to switch out the two domain controllers. I'd like the new servers to run Windows Server 2008. Could you please give me some insight of what needs to be done so that the domain controllers can be switched out without any interruption to users, as far as them being able to access their e-mails, logon, etc.