How long before the electronics industry makes a major breakthrough in battery power? In the meantime, power-conserving computer chips can do more with less -- at least if Intel's Pentium M is any indication. The low-power processor shows up in IBM's ThinkPad X31 and delivers impressive working time in an ultra-lightweight system. The X31 that we looked at was configured as a true-blue Centrino, although you can also specify IBM's 802.11a/b wireless and built-in Bluetooth. Beyond its 3.5-hour battery life (6 hours with a second battery fitted), the X31 offers flawless design and flexible configurations. The ThinkPad X31 makes a desirable package for someone who travels a lot and relies on long-running batteries.