Getting optus ADSL working on Ubuntu

Hi all,
Firstly, I am by no means an expert in linux so feel free to point out the "obvious" :)

I set up a ubuntu machine for my dad who is a 2 hour drive away from me.
I have optus cable so it works straight out of the box but he has optus adsl and it doesnt work.

Using network-manager-gnome we checked the ip settings which all seem to be good. An ip is assigned via dhcp in the 58.xxx range and the primary and secondary dns servers seem fine.
The only thing I could find was that eth0 was not set as the default gateway device which we did via the network settings panel.

Still we cannot ping google.com.au either by ip or by name.

Any help greatly appreciated.

Cheers
JB
.