|lets start at the basics|
usually you wire cable tv, network, telephone [which includes dsl] all to one point in the house [closet] or garage. Usually as close as possible to where the cable/telephone comes into the house or where it is practical to have all connections from inside the house terminate.
These are wired to a distribution center.
Networking would be to a punchdown block same as telephone except it has rj45 ports.
Incoming cable goes to a splitter for x number of rooms.
We will call this the network center.
This should be professionally done!!!
You wire every room with all three, network, telephone and cable.
Places like living room [entertainment center] you double/triple up on cable and network.
In the network center you install your dsl modem which connects to your dsl router. Using a patch cable you go from routers lan ports to the punchdown panel containing the rj45 ports. This connects the jack in the room you desire connected to the router.
In the room you take a patch cord and connect your pc via its rj45 nic.
you can wire multiple ports in a room if you want multiple devices networked.
Or you can use a crossover cable to connect a switch into this room. The using patch cords you connect your xbox and pc to the switch. If the switch has a uplink port or supports mdix you can use a regular patch cable to the wall port.