Joe Belfiore, corporate vice president of Microsoft's Windows eHome Division, disclosed the sales numbers at a keynote speech here at Mix '06, a Microsoft conference aimed at Web developers and designers.
Belfiore also demonstrated the upcoming enhancements to Media Center, which willearly next year, saying it will "blur the line between television and interactive video content."
Sales of Media Center, a higher-end version of Windows XP for handling multimedia content, were sluggish in the first few years of its life but have picked up as Microsoft has cut prices and dropped a requirement that PCs that run Media Center come with a built-in TV tuner.
Belfiore said sales of Media Center are now running at 1 million units per month and that the company is "highly confident" total sales will top 10 million by the end of the month.
Citing third-party research, he said 59 percent of PCs sold through retail outlets in the U.S. were Media Center PCs. On Monday,said sales of Media Center PCs in December of last year made up more than 40 percent of all Windows sales.
With Vista, Microsoft doesn't plan a distinct Media Center Edition but instead is including capabilities such as video recording in both the Home Premium version of Vista as well as the Ultimate Edition, which combines high-end consumer and business features.
With the Vista release of Media Center, Belfiore said, Microsoft is planning to improve video viewing, create close integration with its Xbox 360 game console and significantly expand the distribution of the product worldwide.
He said that Windows Vista Media Center PCs will have support for digital cable, allowing people to view high-definition television from a PC.
Also, Windows Vista will take better advantage of large screens to help people manage large libraries of photos, videos or music files.
Belfiore demonstrated a number of applications that were written with Microsoft developer tools for Windows Vista.
He said the Windows Presentation Foundation, the user interface toolkit to ship with Vista, will let people easily convert existing Windows or Web applications to run with a remote control on a television or Xbox console.
"The idea is to get content out of the PC and onto the TV and through a range of devices," Belfiore said.
One attendee who consults for a multinational media company said the slick user interface design enabled by Microsoft's upcoming operating system will appeal to many people.
However, he said, some of the restrictions placed on video content, in the form of Windows file formats and digital rights management, could be frustrating to some.
"If I have a video that I want to share with someone, and they can't play it except on Media Center, people are going to get frustrated," said the attendee, who did not want to be quoted by name.
CNET News.com's Ina Fried contributed to this report.