The company has scheduled announcements on Sept. 30 to take place simultaneously in four cities: New York, San Francisco, Los Angeles and Redmond, Wash.
At the September events, Microsoft will display the upgrade to the Media Center operating system, code-named Harmony, according to sources.
The specialized version of the Windows XP operating system provides an extra interface to make it easy for people to view photos, listen to music and watch videos on a television hooked up to the PC.
Microsoft launched Windows XP Media Center last October, with Hewlett-Packard offering the first systems with the software. Gateway and games PC specialist Alienware--among others--followed suit with their own Media Center desktops, while Toshiba has begun selling laptops running the operating system.
Executives at Microsoft have promised that the Redmond, Wash.-based company will expand Windows XP Media Center to more countries, in Europe and Asia, before the end of the year. So far, Media Center systems are available only in North America and Korea.
Earlier this summer, Microsoft pledged to make improvements to the operating system, but said only that those changes would come by the middle of next year, at the end of its fiscal year.
Hardware makers are expected to show off new PCs using the upgraded Windows XP Media Center at the Sept. 30 events. HP has said it plans to bring out its first notebook computer with the operating system this year.
The software maker declined to provide details on the September events.
Microsoft has not said how many Media Center PCs have sold, but IDC analyst Roger Kay recently estimated that it is in the high tens of thousands.
"I expect them to have much broader industry support in this round," Kay said on Thursday, referring to the expected fall release.
At the September events, Microsoft is expected to announce that it has won over hardware makers that previously took a pass on offering Media Center PCs, sources said. Although the software maker has landed some big-name computer makers, others have taken a "wait and see" approach.
Microsoft is likely going to add streaming media content to the new version of Windows XP Media Center through deals with partners, according to a source. The source noted that many early customers have not fully used the operating system's media-playing capabilities.CNET News.com's Richard Shim contributed to this report.