if you have two modems you will pay double you're cable bill and it will be like you have to pay two internets. Also idk if you have a router and just made a mistake or if you only have a modem but modems don't have wireless capabilities routers do. You'll have to get a router, hook that up to the modem, and then run a wire from the router to your xbox 360. Wireless is unstable

To the poster above, what kind of router do you have? You can block your neighbors from using your connection by putting a password on your router. Which I would highly suggest because your neighbors could be using your connection for illegal activities and/or be seeing the logs of all websites you go to very easily. ( you can also see all the ones they go to)