Exchange 2000 and Exchange 2003

We currently have 1 Exchange 2000 server running on a Windows 2000 server. [We have 1 Windows 2003 Doamin Controller, plus other Win2000 DC’s.]

It is possible to add a second server– with Windows 2003 and running Exchange 2003– and keep them in the same “Administrative Group”?
I will also need the ability to do a mailbox move from 1 server to the other, but I think that should be possible when they are in the same Administrative Group.

Any help or advise is greatly appreciated.