Outlook and Peer to Peer Network

A client has a peer to peer network of 5 or 6 computers and they want to share Outlook 2002 folders.
They are not willing ( understandably ) to spend $2200+ on Microsoft exchange.

Is there a program available that will allow sharing of the Outlook Calendar ( and maybe contacts list ) over a peer to peer network?

Hope someone has an idea 🙂

Regards to all