Currently Being ModeratedMar 14, 2013 11:08 AM (in response to AZ-Birdy)
Any time you change networking hardware it is always a good idea to perform a complete power recycle of your networking equipment. Please check out the following AirPort User Tip for details.
Currently Being ModeratedMar 14, 2013 1:19 PM (in response to Tesserax)
I figured it out. I needed to register my new Modem with my ISP (Cox). Once they logged in the Model/SN everything was Happy. My Airport Express configured itself upon restart.