Suggestion:
you need to create a bridge by right clicking on the wireless connenction and the local area where you have the ethernet going from the laptop to the xbox. you have to do some adjustments with xp by choosing the advanced settings and clicking "shared" and i forget the other box, something about allowing others to control your connection, this will let your signal be stronger for live. it works, ive done it, it may take some medling with tho
