Microsoft will to extend its Xbox Live online gaming and entertainment network to Windows in May as part of its plan to offer more Web-based services through its desktop OS.

On May 8, Microsoft will launch the Windows Vista version of the popular Xbox game "Halo 2" with the addition of what the company is calling Games for Windows -- Live, which connects gamers to more than 6 million other players in the Xbox Live community, Microsoft said. In June, Microsoft will release a second game for Windows Vista that incorporates Games for Windows -- Live, "Shadowrun," with a third game "Uno" to be released later this year.

Microsoft has been ramping up its plans to offer online services branded with the "Live" moniker, and its Xbox 360 and Windows gaming platforms are included in that strategy. Online services such as Xbox Live, which allows gamers to play online against other players and offers a games and entertainment marketplace, enables Microsoft to sell more advertising online. The company is in pursuit of Google Inc. to boost its online ad revenue.

With the new Games for Windows -- Live platform, people playing games on the Xbox 360 can connect seamlessly to gamers who are playing on Windows Vista. Users also can get a single identity, friends list and other services that log their gaming history across both Xbox and Windows platforms. Additionally, Xbox Live functionality such as such as in-game voice chat, integrated achievements and dedicated servers now will be offered on Windows through Games for Windows -- Live.

Current members of Xbox Live will immediately receive the functionality of Games for Windows -- Live using the same gamertag and friends list at no additional cost, and the pricing of the Live services across both Xbox and Games for Windows is the same, Microsoft said. The company also will offer both Silver and Gold memberships for the Windows platform as they do in Xbox Live.

There is no cost associated with signing up for a Silver membership. Gold memberships cost US$49.95 per year; however, current Xbox Live Gold members will automatically have access to Gold features on Games for Windows -- Live titles, Microsoft said.