Two network cards, ADSL & DHCP working, but can't share internet

[Hammy15]

Installed a fresh Kubuntu 7.04 with 704 LinuxMCE.

Had earlier tried this and then connecting to ADSL, but couldn't get it to work.  This time I set-up ADSL after Kubuntu, but before LinuxMCE.  So my LinuxMCE core can connect to internet.  However, other computers the connect to the core (now only one direct as I removed my switch to reduce variables) can't connect tot he internet.  It can ping the core (and vice versa), but not outside sites.

I disabled core firewall, but still can't get anywhere.

In terms of DHCP addresses assigned, I'm not sure whether other computers are pluto or non-pluto devices, but I tried it both ways without success.
Any help appreciated.