Networking & wireless: Connecting Cable Modem (Arris TH608g) to US Robotics Router

Connecting Cable Modem (Arris TH608g) to US Robotics Router

I'm unable to get my US Robotics MaxG Router(USR 5461) to behave nicely with my cable modem (Arris TH608g).

When the modem is connection from my wall jack into the PC (running Vista), I have Internet connectivity. Whenever I attempt to connect the same PC network cable from the wall jack into the WAN port on the router, there's no Internet connectivity. I'm able to connect to the router's GUI. However, I'm not able connect to the internet.

Things I've tried:
* Resetting the modem with router connected only
* Disconnecting and reconnecting the modem's power cord
* Disconnecting and reconnecting the modem's battery
* Power cycling the router
* Mac Clone via the router GUI
* Calling the ISP - dead end [they don't support 3rd party routers]

I would prefer not to get hacked for a monthly service fee for using the ISP's modem/router to possibly get a more ideal home network environment with multiple computer internet access.

Any suggestions will be welcomed.