Western Digital has announced its first foray into mobile hard drives. If the new drives live up to their promise, they should be among the best options available.

Mobile hard drives have always lagged behind 3.5-inch desktop models in performance and capacity, partly because of their smaller, 2.5-inch size and their need to conserve notebook PC power. But the higher-performance, power-thrifty Scorpio models should do much to narrow the performance gap.

The Scorpio line of drives debuts in 40GB, 60GB and 80GB capacities. The drive has a rated average seek time of 12ms and comes with a 2MB buffer (an upgrade to 8MB is optional). Like competing high-performance models from manufacturers such as Hitachi and Seagate, Scorpio drives will spin their platters at 5400rpm. Such high-speed spinning presents special problems with heat buildup, power use and sound volume. The company says that it has solved all of these problems.

The company claims that models in the Scorpio line are the quietest mobile hard drives on the market. Heat won't be a problem either, according to spokesman Darrin Bulik. "Scorpio has run cooler in our tests than the competing 4200rpm and 5400rpm models we've compared it to," he says.

Aside from heat issues, power consumption is perhaps the biggest concerns for notebook computer users. Western Digital reports that Scorpio drives should be very miserly in their use of energy, taking roughly the same amount of power as 4200rpm drives while running far faster.

The drives began shipping in volume to notebook manufacturers today, and they should be available to notebook buyers within the next month or so, Bulik says. He declines to name notebook vendors that will be selling models incorporating Scorpio drives, though he does say that the drives are in qualification with all of the top ten vendors, among others.

With the market growing at about 20 percent annually, according to industry research analysis firm TrendFocus, demand for mobile hard drives is increasing. Western Digital's customers have been urging the company to offer mobile drives, says Bulik. With their strong resume, Scorpio drives are likely to thrive under these conditions.