If you can get to both the router and the CM from your PC, and the router is showing a valid NTL IP address, eg 80.x.x.x, there
shouldn't be a problem.
Is there no traffic getting out? The usual test's are
Tracert
www.bbc.co.uk
and
telnet
www.bbc.co.uk 80
from the Dos prompt.
Does 'can't access the internet' mean just browsing or everything?