SBS 2000 Exchange: Moving Mailboxes

Our company is planning a movement of exchange data from one SBS 2k Server to another 2k server. All of the mailboxes will be the same. The only change is that we have a new physical machine that we are putting in as the server. The new machine is not the same internally as the old one. What is the best strategy for moving Exchange from one server to another? The new machine has no operating system on it yet, because we aren’t sure whether to put SBS or just 2K server on it before the transfer of Exchange data. Thanks for your help.