You need an ethernet hub, or switch, and you plug the cable modem into that, and the airport into that, and the other machines into that. LO, you set up airport to ethernet bridging (enable) you use the ABS to do DHCP and NAT. The public IP from the cable modem is given to the ABS, which runs NAT, and redistributes private 10. IP addresses over the same hub/switch. No router required. Some comments.... 1) make sure that if you use DHCP to give the IP addy to the ABS from the cable modem, that it is the ONLY ethernet mac address that the cable modem sees as it powers up. potentially use static addys on the 10. network.

Bleh. It works, but its messy. You save $150 on a router. YMMV.
(it slows the ABS file transfer from machine to machine to a crawl too)

Ben.