After struggling with the our old portal I realised that I was spending all my time just maintaining the system rather than contributing any content!
So after reviewing options I have re-platformed the portal based on TYPOlight technology. This seems a reasonably simple to use but powerful option; open source but with paid for support options - it is based on PHP.
Currently I have spend a few "fun" hours copying all the content across and making sure the basic functionality works.