Games for Windows – Live (officially spelt LIVE) is an online gaming service for Games for Windows-branded PC titles. It enables Windows PCs to connect to the Live service, which will eventually include other devices including Windows Mobile and Zune. Users, each with a unique Gamertag that carries over from Xbox Live, will be able to play online, keep track of their friends' status, send and receive messages, gain and keep track of Achievements, voice chat across platforms, and more. Some games will allow for cross-platform play, such as Shadowrun, which allows PC players to compete against Xbox 360 players.
Games for Windows – Live is currently only available for the Windows Vista operating system. But, it has been announced that Microsoft plans to bring it to XP late this year. Its features will initially be limited, but will grow just as the features of Xbox Live have over the years. The service was shown in near-final form at CES 2007 during Bill Gates' keynote speech.
The service will be open to 3rd-party developers, but they must be able to meet certain requirements, which could include game ratings, total number of achievement points, and the ability to properly connect to Live.

Products
The user interface or "Guide" follows much the same layout as the Xbox 360 version. Apart from minor cosmetic differences it also matches the same features as the Xbox 360. This includes messaging (text and voice), friends list, recent players, private chat and personal settings.
The client that provides this interface is included with Games for Windows – Live games. It is only available when running a game designed for the service. Access to Live functions outside of games is not possible although a Windows client similar to messenger is under consideration for future versions of the service.
The current version of the in-game Live client is 1.0.6027, released on April 30th 2007. The client will update when you log into a Live-aware game, or you can download it manually here.

User Interface
Games for Windows – Live Silver Membership Features
Games for Windows – Live Gold Membership Features

Single gamertag
Common gamer profile
Common gamerscore
Single player achievements
Private chat via text and voice
Common friends list and online presence
PC only multiplayer including browsing a list of active PC games
All Silver membership features
Multiplayer matchmaking with friends
TruSkill matchmaking
Multiplayer achievements
Cross-platform gameplay Differences between Gold and Silver Memberships
Games for Windows – Live uses the same pricing structure as Xbox Live. The silver level service is free, while the Gold level requires a regular subscription. The gold subscription pricing is below:
Memberships can be purchased either directly from the interface (credit card required), or as prepaid Xbox Live cards at retailers.
Games for Windows – Live and Xbox Live are essentially the same network, so subscribing to one automatically gives you access to the other, therefore current Xbox Live Gold subscribers will get access to Games for Windows – Live Gold and vice-versa. In addition to shared subscription, all achievements, friends, players and messages pool together across both platforms. [5]