I have a LinkSys router with the WAN side connected to a cable modem, and the LAN side to the Untrusted interface on the firewall. The trusted interface goes to a NetGear 4 port hub. The WAN side of the LinkSys gets it's IP address via DHCP, the LAN side is 192.168.1.1:255.255.255.0, The Untrusted interface is 192.168.1.2:255.255.255.0. With the LAN side of the LinkSys set as the gateway. The Trusted interface is 192.168.123.65:255.255.255.192, and the Untrusted interface set as the gateway. PC's on the lan are in the 123.xx subnet with the Trusted interface as the gateway.
What other information can I give you? Like I said, I had it working at one point. I've even uninstalled and re-installed, but I still haven't gotten it to work again.
Thanks