Hitachi Global Storage Technologies plans to announce a 40GB drive for notebook computers meant to better withstand harsh treatment. The company, which recently introduced massive 400GB and 300GB drives, hopes to build on its leadership in the fast-growing laptop drive market with the new 2.5-inch product, according Zdnet news.

Hitachi is focusing on features such as greater shock tolerance and better durability when it comes to moving the read/write head on and off the disk media, the sources said. The new drive, which spins at 4,200 revolutions per minute, is designed to tolerate a shock of 300 "Gs" for 2 milliseconds while operating. That's 50 percent higher than the tolerance of Hitachi's previous-generation 40GB, 4,200 RPM drives. The new product is also built to handle 600,000 "load/unload cycles" without failure -- twice that of the previous-generation Hitachi drives.

Hitachi and other companies already make "mobile" hard drives that hold 60GB and 80GB. But "40GB is the sweet spot today," said a source close to Hitachi.

40GB drives accounted for 44 percent of the notebook drive market last year, and the number will jump to 60 percent this year, as shipments of less-capacious 20GB drives peter out.

Hitachi's new drive is expected to ship in volume quantities in April, according to the sources. The new 40GB drive is priced at $139 (£76), the same as the previous-generation 40GB Hitachi drive, the sources said.