Valve has introduced something very much like Xboxlive. Messages back and forth, your own personal community page, friends list. But I don't have to pay a dime for the service. Hell, you could just download Steam for free and sit at your computer staring at the screen. I don't pay for Xboxlive because all the multiplayer games are years behind most PC multiplayer games.
Halo 3 is arguably the best multiplayer experience on Xbox. I played the singleplayer game, used up my 24 hour pass of free xboxlive to play multiplayer and became frustrated with the menus. Not being able to select a SPECIFIC game mode to play and no server browser really irked me. I traded that game in and shoveled out some cash for Call Of Duty 4 on PC which I'm very glad I did. 10 dollars cheaper and free online play.