According to Pete Hines, PC users will be the first to enjoy downloadable content for Fallout 3. From Videogamer.com:

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."

I hope they make the game playable before any DLC comes out. A mega patch should be an absolute priority right now.

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