The SSD is based on the same flash-memory technology found in the widely used USB memory keys. Where a conventional hard drive stores data on a magnetic disk that spins at up to 7,200 RPM, the SSD is basically a handful of chips with no moving parts.

Flash has been around for years, but two considerations blocked its use for mass storage: cost and the fact that you could only rewrite your data a limited number of times. Even now, flash memory costs far more per megabyte than magnetic storage, but chip prices have been plunging.

As for the limits on rewrites, manufacturers have greatly improved the situation by spiffing up the semiconductors and adding software that makes sure the data in any one chip location aren't changed too often.

From a PC user's point of view, the benefits of moving to flash include greater reliability, lower power consumption, and faster performance, especially at startup. The shift to SSD could also enable the design of smaller laptops. And there would be side benefits: A ramp-up in flash memory across the tech sector would bring chip prices even lower, which would inevitably beef up the storage capacity of mobile phones, music players, and other handheld devices.

Worth the Cost?

For now, at least, there are significant drawbacks to the flash approach. The most important remains cost -- close to $500 for a relatively small 32-gigabyte drive. That's about five times as much as a conventional unit. SSDs should get more capacious and much cheaper as their use expands.

I tried two SSD-equipped laptops. One was a Dell Latitude D420 notebook with a 32 GB SanDisk SSD as a $450 option. The other was a prototype subcompact notebook Samsung provided me, rigged with one of its own 32 GB SSDs. These two notebooks, both running Windows XP, showed a big performance gain, mostly in the form of faster boot times and, especially, faster wake-up from hibernation.

They also gained a bit of battery life, perhaps 15 or 20 minutes on a charge. I'm not sure that's worth the extra cost, though there's a clear benefit in eliminating the mechanically fragile hard drive in a PC like the Dell ATG for rugged use, which also has an optional SanDisk SSD drive. (continued...)