This is what we found out at the Games For Windows Live site.

Games for Windows – LIVE, the free gaming service built for Windows that makes great Windows games even better.  With Games for Windows – LIVE, you get an online identity – called a gamertag – and a friends list that works across multiple games, the XBOX 360, and even the Zune music service.  You can easily find and communicate with your friends online with text and voice chat.  Earn achievements and Gamerscore that lets you track and compare your accomplishments. 

Play multiplayer games with your friends, or play against new opponents online using our exclusive TrueSkill™  matchmaking system – with other Windows® players or with or against XBOX 360 players (in supported games.)

All of this is possible today – and at no charge.

Every Games for Windows- LIVE game carries the Games for Windows branding, which means they meet standards for quality, consistency, safety, and ease of play.  Games for Windows games are tested to support wide-screen monitors, 64-bit operating systems, parental controls, and, in appropriate games, the Xbox 360 Controller for Windows.

Games for Windows – LIVE lets you add achievements and gamerscore earned in Windows games to your XBOX LIVE account. You can also chat and message your friends on LIVE, regardless of the platform.

The stability and functionality of the Xbox LIVE service provides Games for Windows – LIVE players with a constant, feature-rich platform that already supports a community of over 12 million gamers.  Come join the fun!

And - Games for Windows – LIVE will soon be the best place to download additional content for your favorite games, from game trailers to playable demos to new maps and levels.  Extending your game experience will be easy with Games for Windows – LIVE.