How did you connect your modem directly? It's best to connect your Xbox using a router, or on a hub using ICS. There's a tutorial on X-S about networking your xbox, I think. DNS is also important as this will translate a URI to its corresponding IP address. And 0.0.0.0 for an IP means, the networking stack failed to get a valid IP, thus, it isn't even initialized at all. You can use any static IP and provide a valid DNS. You can get a valid DNS address if you open a command prompt and type "ipconfig /all" if you're machine is connected to the internet.
