Migration to Exchange 2000 Across Domain

We currently have an NT 4.0 Domain that has Exchange 5.5 running in it. We have created a new Windows 2000 Domain that we will eventually move to. I have done quite a bit of research with regard to migration but have found very little information on the best way to migrate 5.5 users mailboxes to the new Exchange 2000 box across domains. I would prefer that for now they remain in the NT 4.0 Domain and get access to the new mail server in the 2000 domain.

I have been experimenting with the ADC and Migration Wizard and have the basics down. Is there a way that both mail servers could be running at the same time in different domains synchonized so that I can move users gradually? I don’t need the small details. An overview of the best process that allows gradual migration will serve me the best.

Dan Cassat