Place to go to ask questions about gaming systems

The only USB wireless adaptors that work for the xbox are the ones that are made for it. Although, I'm pretty sure the new xboxes have them built-in.

An alternative. I'm not 100% sure on this but I think you can get a second wireless access point/router and bridge it with the first and then connect it to the ethernet port on the xbox.
Of course, you would need to go to the expense of getting a second access point/router and the hassle of setting it up.