Microsoft Corp., the world’s largest software maker, said on Monday it plans to offer a streaming video service that stores and hosts video for its new Silverlight online media platform.

Silverlight, which is now available for download in a test version, is a rival to Adobe Systems Inc.’s dominant Flash player and a new application to deliver video, games and animation through a Web browser.

Silverlight Streaming by Windows Live is one of the first applications announced by Microsoft to take advantage of the company’s heavy investments in building a data center infrastructure backbone for its Web services.

The company said it will store and host up to 4 gigabytes of video for Web developers.

“You should consider this as a sign of things to come in terms of our software and services platform,” said Ray Ozzie, Microsoft’s chief software architect, in a keynote speech at its MIX 07 conference for Web developers and designers.

Microsoft has invested billions of dollars in building a network of massive data centers filled with computer servers, data storage and network systems to provide the company with the computing power needed to compete with leading Web services provider Google Inc.

The company’s “software plus services” strategy aims to bring a host of new Web services — some supported by subscriptions and others provided for free with advertising — without compromising its cash cow desktop software business.