I just got an Airport Extreme which I want to use to setup a local network in my house, to share a HDD and allow communication between iPhone and MacBook Air. Set up the wireless network, connected HDD, all seems okay. Except for this -- I connect to the Internet via a USB-key which must be plugged into the MacBook Air. Whenever the wireless is turned ON, it blocks the USB key Internet connection. There must be some way to do this -- so that Internet apps know to use the USB Key rather than the wireless network to connect. (On a PC I would know how to do this), but I cannot see how to do this on the Mac. Can someone tell me or point me where to find the answer? Thanks.