What is the best way to set up the Microsoft Outlook Calendar on a
pier-to-pier network?  Am I better off getting an exchange server, or
should I buy third party software to get the two to communicate with
each other?

Hi,

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You can replace Outlook with this server...

There were a couple of ways to make this work 5 versions ago, but
really, the simplest answer if you want to use outlook, is MS Small
Busines Server 2003  which includes exchange server (and outlook for
that matter).

Otherwise, for a peer to peer, I once upon a time supported a network
running Time & Chaos, which worked quite well, though the customer
later converted to outlook/exchange.  Just requires a shared directory
all pc's can access. www.chaossoftware.com