Are you already using Windows file and printer sharing?
If so I would suggest keeping your Outlook.pst (and Archive.pst) files in a shared directory on your main computer.
Then you can permanently map a network drive to this directory on each of the other computers. And tell Outlook on each of those to look in this location for Outlook.pst (and Archive.pst). You can tell Outlook where to look for these files by right-clicking on the Outlook desktop icon. Choose Properties > Data Files.
However, you could run into trouble if you have Outlook running simultaneously running on more than one PC and they simultaneously try to access these files.