Easiest way:
hire a contractor, Seriously.
If you want Exchange 2k you will have to upgrade your domain to Active directory. Easiest way to do that is; Install a new nt4 BDC with nothing on it, Sync the domain, Upgrade it to Win2kServer.
Considerations:
-Do you already have DNS?
-Do you have an internet presence?
-Do you have multiple sites? if you do hire a contractor.
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