Exchange Server move to new computer

I need to know how to move my exchange server information from an old server to the new one that I have set up. We are running NT4.0 and Exchange 5.0. We have Internet e-mail running. I have the new server up and running, though I’ve not installed Exchange on it yet. I want to migrate all of my users mailboxes etc. to the new machine. I am assuming that the basic NT user info will be on the new machine because of replication. The server has been running on my network for quite a while now.