It should be fine. You will have to set up your internet connection on the X-box anyways in order to get your x-box online. Once that is set up is finished you should be able to unplug the cat5 cable coming from your modem and plug it either into your computer or your x-box. There also should also be no problem when switching it back and forth. Of course you will have to decide what you want more the computer to be online or your x-box. I would suggest just buying a router and another cat5 cable. There relatively cheap.

no clue =]