HD Install :: DHCP not connecting

DSL 3.2 syslinux when used 'live' on a an old desktop with no other OS installed and connected to a Linksys router, there is no problem making an internet connection. Yet on a HD install I cannot get past the router. I have used Netconfig to try various configurations of DHCP (including 'auto').
Since the network card works 'live' what am I missing to make it work as a HD install?

I am having the same problem on a USB installation, can anyone help?

original here.