Service also described as an 'integral part' of many titles.
Microsoft has confirmed that Fallout 3 will be the first title to offer DLC through the newly announced Games for Windows LIVE Marketplace.
Pete Hines, vice president of public relations and marketing for Bethesda Softworks commented: "Games for Windows LIVE helps us expand the Fallout 3 universe and bring the full experience directly to gamers. Through the Marketplace we now have a no-nonsense way to deliver updates and great downloadable content. It's really a complete package, and a great fit for Fallout 3."
Other titles, both current and coming soon, that offer support for Games for Windows LIVE include Grand Theft Auto IV, Quantum of Solace, Warhammer 40,000: Dawn of War II, Red Faction: Guerrilla and Battlestations: Pacific.