I have DSL. I have two computers connected to a Linksys BFSR41 router. The router is connected to a Thompson modem which is connected to the Internet. My ISP uses PPPOA authentication. The modem has a NAT firewall and does the dialing. My router is set to obtain an IP address automatically. With my router set to obtain an IP automatically, I believe it is merely acting as a switch. My question is this - is the NAT firewall in my router still functioning? What about the NAT firewall in my modem? Can both firewalls work simultaneously?

Thanks.