Problems with underscores in Computer Name for Server 2000

Does anybody know how to put underscores in the name of
the computer when installing Exchange onto Server 2000.
Unfortunately the name of our old server had underscores
in the title. Whenever we try to build a new server with
the same name as the old server, the Exchange
Installation complains. We have no idea how the original
server was built with underscores in the computer name,
although it is rumoured that Exchange 5.5 allowed these.

As a result of this, we cannot retrieve the old Exchange
mailboxes, because the new server has a different name to
the old server.

Alternatively does anybody know how to restore exchange
file from one server (which is now dead) to a server with
a different name.

Any assistance would be greatly appreciated.

Thanks,

Dave