MACDRIVE Im having the same problem I keep loosing connection to the internet. SBC blamed the Modem, so I bought a new one (paid $150) my connection continues to drop just 5 days after I installed the new modem. wasted $150 on a Modem I did not need. Ran numerous hardware test. called Apples technical support, And SBCs technical support, still no go. I bought Monster surge protectors, along with some brand new phone wires, then went through the phone book called a place in my area that fixes computers. The technician Re wired the room where the mac is connected, still no go. The Mac still continues to loose internet connection just a few days after the tech rewired the entire room. I think the problem has something to do with this... Air port confusing my Wired connection with a Wireless.
Also A lot of people that use SBC as a ISP are having the exact same problem, no doubt its either this Airport thingamajig Or SBC causing this to happen.