Remember when VHS videos whupped the pants off Beta? You had to replace your VCR as well as any Beta videos you owned; it was a pain in the home-entertainment system. Then CD-ROMs became all the rage on your computer, and you suddenly needed a PC that allowed you to steer a CD drive. Now, the past-blasting technology of DVDs is replacing CD-ROMs, and we're all facing another expensive high-tech revolution.

So what's the score? Is it worth switching? Will DVDs last? Yes, yes, yes. DVDs are vastly superior to CDs in their data-storage capacities, their data-retrieval speeds, and their versatility (DVD drives can read both DVDs and CDs).

The secret behind DVDs' superiority is their similarity to CD formats. To the naked eyeball, CDs and DVDs look the same. Under the microscope, both CDs and DVDs are made up of flat surfaces ("lands") interrupted by bumps ("pits"). Both CD and DVD drives read pits and lands as the ones and zeroes of binary code that send instructions to your computer. Both CD and DVD drives send lasers onto the surface of the disc, and depending on the intensity of the reflected beam (hitting pits diffuses the laser and sends a weaker signal back to the drive), determine whether they've hit a land or a pit.

The difference is the relative size of these pits and lands. The pits on a DVD are about half the size of those on CDs; and they're packed between lands that are much narrower than those of CDs. In addition, DVDs can be "pitted" on both sides, with each side holding up to two separate layers of pits and lands. CDs, by contrast, can only store one layer of data on one side of the disc.

Microscopically that all means....