Microsoft Corp. on Tuesday unveiled a new version of its Windows XP Media Center, adding features such as instant messaging and high-definition television to a personal computer designed for the living room.

The PC, which hooks up to TVs and allows users to view movies, listen to music and flip through digital pictures with a remote control, was introduced in 2002 and is one of Microsoft's biggest bets to breathe new life into personal computer sales.

The world's largest software maker said it will back up the new version with a $100 million-plus marketing campaign.

Windows XP Media Center Edition 2005 is at the heart of Microsoft's vision to offer people around the world the best in complete, connected entertainment experiences," Bill Gates, Microsoft's chairman and chief software architect, said in a statement ahead of a media event in Los Angeles.

Windows Media Center's nearest competitor is Tivo Inc.'s hard disk-based video recorder, which allows users to pause and record live TV and save scheduled TV programs.

Media center PCs, which are mostly priced between $1,000 and $2,000, also allow users to listen to music stored on hard drives, view digital pictures and access a variety of other content.

The new Media Center offers the ability to swap instant text messages while watching TV, record and play back high-definition video, as well as a more advanced programming guide that allows users to search for movies.

Since Windows Media Center's features are closely tied to the hardware, it won't be available as a separate operating system but instead will be sold by computer makers such as Dell Inc. , Hewlett-Packard Co. , Toshiba Corp. and Sony Corp.

In addition, cheaper component prices are expected to spawn some players under $1,000, and better designs are resulting in small, quiet computers that can be stacked along with other video components.

Computers equipped with the right hardware will allow users to record content onto CDs and DVDs from within the Media Center, access and edit digital photos, and will also include Windows Media Player 10, the version of Microsoft's software for playing video and music on PCs.

One of the key features of all Media Center PCs is a remote control, which brings up a screen to replace the standard Windows graphics with a sleek, simple design that provides quick access to various entertainment media and functions.

One of the key features of all Media Center PCs is a remote control, which brings up a screen to replace the standard Windows graphics with a sleek, simple design that provides quick access to various entertainment media and functions.

At the nudge of a mouse, however, the PC reverts back to the familiar Windows desktop.