"The first key item in this wearable PC is the PC
itself. A device like this needs to be small, pocket sized
preferably, with a good battery life, a reasonable amount of power,
and a good feature set. Years ago, such a device was a pipe dream,
given that batteries, processors, and even the so called "portable
computers" were really anything but portable, powerful, or long
lived. Yet if you look around you right now, that's exactly what we
have. Powerful, portable devices with good battery life. Take for
example your cell phone. Typically, most modern cell phones have
more processing power than most PC's from the 90's could ever dream
of. Even your iPod or PMP likely has more power than they
did."