OK, after wasting 7 hours of my time I thought it only fair to spare somebody the hassle I went through of setting up a Origo 8400 ADSL Modem Router (a bargain at £27.00 NEW) and it works a treat now! I'll keep it very simple.

Step 1: Make sure your TCP/IP settings at set to: Configure: Using DHCP, and
'Network Port Configurations' is set to 'Built-in Ethernet'

Step 2: Type in: into a browser window (this URL only works in Explorer on OSX, Safari doesn't bring up the final screen and Explorer on 9.2.2 doesn't even connect)

Step 3: You should be prompted to add a user name: 'admin' and password: 'epicrouter', then wait a good few minutes. Once this has loaded you will then be asked to add your ISP details and password, which should have been supplied by your ISP.

Step 4: Surf away!!!

I hope I haven't missed anything.