Games for Windows - LIVE is a free online gaming service from Microsoft designed to let you connect and play with your friends and over 14 million Xbox LIVE members.
It's a world-class online gaming network that offers online matchmaking using the patented TrueSkill enhanced matchmaking system. The service offers text and voice messaging across Games for Windows - LIVE and Xbox LIVE.
You can create your own gamertag (online identity) to represent you in all games and platforms. Games for Windows - LIVE and Xbox LIVE share the same network, so your single identity works across Windows, Xbox 360, and even Zune! Earn achievements, build your gamerscore, establish a reputation, and use voice and text chat - even across platforms.