ocelot20:
Sorry but stop giving people wrong advice NO IT WILL NOT WORK with the 360 without the MS wireless adaptor. This is basically a router you cannot just plug this into the back of the 360 and expect it to connect to XBOX LIVE.
You are incorrect, it definitely will work. I have one, and it works better than the MS adapter ever did for me.
It's a wireless bridge. It performs the same function as the MS adapter, except it uses ethernet instead of USB. This means that it can be used with any devices, not just the 360, and it also provides a more stable connection, meaning that you won't get horrible lag spikes like you can with the MS adapter.