Originally posted by: JackMDS
Splitting Network when you have one jack is very simple.
http://www.newegg.com/Product/...x?Item=N82E16833180057
Plug a Network switch to the wall outlet and plug the computer and the X-Box to the switch.
Splitting Internet is depending on how it is configured Now. If you have a Router and the room is connected to the Router then you are good.
Otherwise you have to further explain the whole house's Network setup.
Edit: I see you got already the same answer while I was typing.