this has nothing to do with your problem, but i always use a router, even if i only have 1 computer to connect, simply because it allows you to manipulate your connection in more ways than the cable modem (might not be totally true, but is completely true if you switch cable modems and keep the same router), and it also provides an additional firewall and the availability to share that connection.
i like to have the option to share the connection, cause it kinda sticks one to the man. the cable companies want you to pay for multiple connections. =)
arbitrary anarchy FTW!!! =D