Exchange Upgrade

We are upgrading our NT 4.0 network to W2K. Because our old NT servers are not W2K compliant, and we need to change our domain name, I have installed BackOffice 2000 on a new server as a new W2K domain. We are starting from the ground up with a new W2K domain. My question is: Is there a way to migrate the mailboxes and public folders from Exchange 5.5 in our old NT domain to a new Exchange 2000 server. From what I have read, this requires both the Exchange 2000 and Exchange 5.5 servers to be inthe same site to do a move mailbox and move public folders upgrade. I am not sure that I can join these in the same site. I would appreciate any tips, pointers to information or other suggestions how to accomplish this.