They do offer such a thing. It is called Exchange Server.

Seriously, though, archiving out to PSTs - especially when stored on a network drive - is a horribly inefficient use of network resources to get at email data. If you need the data on multiple PCs, keeping it in Exchange (or some other online/hosted environment) or struggle with syncing your PSTs manually. Since they're each a database file if you aren't careful you end up with the mess that cordelli describes just above when you get out of sync.