The IBM ThinkPad R50 notebook ($1,769 direct, tested configuration) knows when it's falling. IBM's new drive-protection technology senses rough handling and parks the hard drive heads. Should the notebook hit the deck, the drive and its data are likely to remain intact, even if the computer itself is damaged and becomes unusable.

The Active Protection System is the most fascinating attribute of the new R50, which could be the most desirable of today's value notebooks. The R50 has many parts and features, including the Active Protection System, in common with the flagship IBM ThinkPad T41, but saves you about $400 for a comparably equipped unit. The trade-off is bulk—an extra pound of weight and one-third more volume. But a company can employ a strategy that outfits its mainstream users with cost-saving R50s, gives T41s to those who require a little more performance and a lighter load, and supplies 3.6-pound X31s to road warriors who need only one internal drive bay. Then the IT department can share the same master copy of Windows, and distribute, for the most part, the same batteries, optical drives, and modules. (Commonality of software, drives, and docking systems is not exclusive to IBM; Dell, HP, and Toshiba, follow the same path, to varying degrees.)

The R-Series actually has some advantages over its top-of-the-line sibling: The R50 comes with either a 14- or 15-inch display; the T-Series offers just the 14-inch screen. And because the R50 uses the industry-standard 12.7-mm removable-device bay, you can swap in a rewritable DVD drive (for $400 more). All you can get with the T-Series is a CD-RW/DVD ROM because of the 9.5-mm bay that IBM hopes will be a standard eventually. One of the only places IBM appears to have cut corners on the R50 is with the PC Card bay—although tall enough to accept two standard Type II cards, it has only one connector, and the extra height is for the handful of Type III (10-mm high) PC Cards still available. Some might consider the ATI Mobility Radeon 7500 graphics controller another cost saver, though.

The R50 is nearly indistinguishable from the T41 in many respects. Both have very comfortable keyboards and offer the TrackPoint and touchpad combination IBM calls the UltraNav. Performance of the R50 we looked at was on a par with systems we've tested in the past from other vendors that used similar components: a 1.5-GHZ Centrino platform, 256MB RAM, a 40GB hard drive, and a CD-RW/DVD-ROM drive. Wireless performance was about average: We were able to maintain a 5 Mbps connection 60 feet from the access point, falling to just over 1 MBps at 160 feet, the most distance measurement point.

The hard drive is mounted on shock-absorbing pads. The Active Protection System comprises IBM-tuned software and a small accelerometer, not unlike that in a car airbag system, which measures sudden sideways or downward movement. Drops of as little as a foot triggered the head-parking system in our tests. You can set the sensitivity to filter out slower motions and to ignore the short, choppy motions you'd encounter flying over the Rockies or riding a train over rough track.

The R50 is available in two models: 15-inch XGA or SXGA+ units measure 1.4 by 13.1 by 11.0 inches (HWD), and 14-inch XGA-only systems are 1.3 by 12.4 b 10.2 inches. Both are slightly bulkier than the 1.0- by 12.2- by10.0-inch T41. For many users, however, the extra bulk may be worth the lower price and the option of a larger screen as well as a DVD-RW, not to mention the ability to protect your hard drive and its data.