The 1.1 title update for PC that was just released today also includes an extra feature — it deploys the Games for Windows LIVE Marketplace app that Fallout 3 will use to release downloadable content for the PC. It will appear as a separate application in your Start Menu under Microsoft Games for Windows LIVE. You can also download the app separately from Microsoft’s Games for Windows site.
To access GFWL Marketplace, you will need to join Games for Windows LIVE, which is free. However, if you’re already are a member of Xbox LIVE (silver or gold), you can use your Xbox Live gamertag and login with Games for Windows Live. Think of this as the PC equivalent to Xbox LIVE. It even uses Microsoft points just like Xbox LIVE.
If you log in using your Xbox LIVE gamertag, it will automatically recognize your pool of Microsoft points, too.
The first DLC for Fallout 3, Operation: Anchorage, will be available on Games for Windows LIVE and Xbox LIVE on Tuesday, January 27th.