Microsoft plans to officially launch today its new Windows Live Search engine, a pillar in its strategy to topple market leader Google and wrestle away billions of dollars worth of online advertising.

Windows Live Search will replace MSN Search, Microsoft's current search engine, in 47 markets worldwide and 23 languages after being available for months in a test version.

Microsoft's market share in Web search is on the slide, ranking third behind Google and Yahoo Inc. with a 9.6 percent share in July, down from 11 percent in January, according to Nielsen//NetRatings. By comparison, Google and Yahoo picked up market share during that period.

"I feel confident that we can gain share," said Derrick Connell, general manager of Microsoft's Search Business Unit.

Microsoft said it aims to improve the search experience by allowing for refined queries and presenting results on a new user-friendly interface.

A few years ago, Microsoft had no search engine of its own and no clear strategy regarding Web advertising, while Google and Yahoo have made multibillion-dollar businesses of search-related advertising.

Since then, Microsoft has become serious about grabbing a larger piece of the $15 billion U.S. market for Internet advertising with an overhauled Web presence under its new Windows Live brand.

A main component of the Internet revamp is Windows Live Search with a new look and features such as easier browsing of searched images, suggestions of related links and a scratch pad to allow users to store pictures and information.

The Redmond, Washington-based company also said it will offer Windows Live Local Search, a mapping service, in the United States and Britain.

Related Link: Microsoft Live