See firewall, no internet

[plug-discuss@lists.plug.phoenix.az.us]

I brought a Linux box from elsewhere to my house here.  It is all set to
network as a DHCP client.  Works fine where it was.

Here at home I have a box running Smoothwall as my firewall and DHCP server. 
Has always worked great with my orignal box that I am using to write this
email.  However, the "new" computer will get an IP address from the DHCP
server and I can ping the firewall or load the admin pages for it from the
"new" box but it cannot resolve internet addresses on the other side of the
firewall.  No internet access.

What configuration files do I need to look at to get full DHCP/DNS support on
this box?   What files should I post here to help you guys help me?  I am a
bit lost because DHCP has always just worked for me, until now.  :^(

Alan