Wow, I am really impressed with the new draft-n stuff. My 1500 minicard just came today and I'm hitting about 234mb/s from a good distance from my router.
Worth checking out if you get a router with Intensi-fi by brodcom.
you can use a regular cat5 cable. to do this, go to your wireless connection and enable ICS (internet connection sharing) then plug the xbox into the ethernet of your computer.
thats the short version, and if you dont understand, I can elaborate...