Western Digital on Wednesday introduced a 320Gbyte notebook hard drive for $200.

The WD Scorpio is a 2.5-inch SATA drive that's slightly more than a third of an inch thick. WD claims it's one of its quietest 5400 RPM drives.

The Scorpio, which has an 8Mbyte cache and a transfer rate of 3Gbits per second, is "extraordinarily quiet while running at cool operating temperatures," according to WD. The drive also uses the company's "IntelliSeek" technology that calculates the optimum seek speeds to lower power consumption, noise and vibration.

The demand for high-capacity hard drives in notebooks and other devices is increasing as the popularity of creating and storing digital photos, music and video grows. "In today's market, new notebook systems are increasingly targeting heavy duty applications in the office and home," Jim Morris, WD's VP and general manager of notebook storage, said in a statement.

The release of Scorpio coincides with new back-up technology from Apple and Microsoft. Apple's Time Machine lets users of the latest version of the Mac operating system, called Leopard, back up and restore the entire Mac to an external USB or Firewire disk, and then access old versions of files or folders, or roll back the whole system to an old state, using an innovative 3-D interface to visualize time. Apple released Leopard last Friday.

Microsoft has released to computer makers its Home Server software for running home network appliances that store, organize, and share photos, music, video and documents. Manufacturers building product around the new OS include Gateway, HP, Iomega, LaCie and Medion. Products are expected in time for the holiday shopping season.