How to create a single login system for wordpress, phpbb and ajaxplorer with openID?

Hi all.
I am creating an intranet as final project of my B.Tech. The intranet is going to comprise:

• A portal made in Wordpress
• Forum made in phpbb
• Public file repository system (ajaXplorer)
• My own custom online test system
• Video streaming server
• Game server

I want a unified login system for the whole intranet. So how can OpenID be used to create such a system? Is ther any other way of doing it?