Ubuntu on external HDD cannot connect to Internet

I just purchased an AAO today - 8GB with Windows XP on it. I usually run Ubuntu from an external USB hard drive, and have had no problem connecting to the internet on a desktop (wired) or a laptop (wireless). When I try either, running my Ubuntu drive on the AAO, I get a notification saying that the network connection has been disconnected. If I click the network icon, I get three options: "Wireless Network" (greyed out), "Auto eth4", and "VPN Connections". When I check for hardware drivers, it says that the wireless driver is installed and activated. I don't know what else to do.

I love Ubuntu and I like the little AAO, but I'd really love to have them work together. I'm planning on uninstalling the pre-installed Windows, but if I'm not going to be able to use the internet...