What system?
PS2
Console
Broadband Adapter
Game
Broadband Connection

in case of xbox:
X-Box Live
Cat5 Cable
Cable Modem
Headset(i believe it comes with X-Box)
Credit Card

If you have a router (to run more then 1 cpu) Get a peice of cat5 cable and run it from the next open slot on your router to th back of your console.
Turn the power button on with no game in it and the xbox live will appear. Install all your information. You wil need a starter key (which can be found in about 1000 games or came with your xbox (if you have a PS2 you don't need 1).
Enter the code, it will then ask you for a credit card.. and get on with x-live.

So wait A minute for the playstation 2 I NEED a computer besides my playstation...cnat i just buy something that connects to the playstation and like sorta of plya wireless , somebody anwser this please...