Sony has announced that it will begin selling an add-on hard drive for its PlayStation 2 video game console next March in North America.

The 40GB attachment will plug into the back of the games console, in connection with the network adapter Sony released last year to enable online play.

The hard drive is designed to enable players to save game settings, to download content such as new levels and characters, and to store music tracks and photos. The first game to use the hard drive will be Square's "Final Fantasy XI," the new online update to the popular series of role-playing games. The title will come preloaded on the hard drive, which will go on sale in March priced at $99. "Final Fantasy XI" and the hard drive have been available in Japan for several months.

The hard drive is part of Sony's effort to keep up with gradually increasing demand for online gaming in the living room. Sony executives said Tuesday the company has shipped 880,000 PlayStation 2 network adapters to date. Microsoft, meanwhile, has signed up more than 500,000 customers for Xbox Live, the subscription-based online gaming service for its Xbox console, which includes a built-in hard drive.

While the initial focus for the hard drive will be on game content, it could also be used to store movies, music and other media items. But exploitation of such multimedia capabilities will partly depend on Sony's coming up with a workable approach to securing such content, Andrew House, executive vice president for Sony Computer Entertainment America, said. That is a particular concern for Sony, given its substantial interests in the movie and music industries.

"With any of the content we'd work with, digital rights management is a very key concern," House said. "We're in a unique position as a company, with businesses on both sides of the issue, as far as being a hardware provider and a major content company."