I ADMIT IT; I’m a gadget freak. My idea of a vacation is to spend a week in Vegas during the Consumer Electronics Show. I like to see who’s fighting the “booth wars” on the convention-center floor—which companies are trying to prove something with bigger exhibits, flashier displays, louder amps, or better giveaway trash. In 1998, it was Microsoft and Windows CE vs. Sun Computing and Java (I still have a closet full of Sun’s Java T-shirts); this year, it was two new companies, TiVo (www.tivo.com) and Replay TV (www.replaytv.com), with a new toy called a Personal Television Server.

Both systems are essentially the same: a set-top box, about the size of a standard VCR, that contains no tape. Instead, it is equipped with a hard drive, modem, and specialized processor chip that allows you to digitally record programs delivered by cable, antenna, or satellite dish. The box includes a dial-up connection to each company’s program database, which automatically downloads several weeks worth of program information tailored for your area sometime during the pre-dawn hours and which sets the clock on your unit. The effect is to turn you into your own digital-video-delivery network. If you decide, say, that you will establish a Pamela Anderson Channel, you simply set up the channel (or “zone,” as Replay calls it) by typing Pam’s name with your remote control, or selecting the appropriate Baywatch episode or satellite-bootleg bedroom video, and the units will search their programming database and automatically record any program they can find with Ms. Anderson in it, without any further effort on your part.

This is the essence of what the industry is calling Personal Television. “It’s like Yahoo! for your TV,” says Jim Plant, Replay’s marketing director. “It’s a portal for television. We’ve all had the experience of getting 120 cable channels and not being able to find anything we want to watch. Replay lets you pick a show once, and then lets you decide whether you want to keep recording it every week, or even set up a ‘zone’ that will record anything that features that actor or show.”

Both units use a format called MPEG II to record in digital video, and although you can store anywhere from six to 28 hours of recorded programming on a Replay drive, or 14 to 30 hours on a TiVo drive (the range depends upon how much you spend), Replay has connections for additional storage drives—although such drives are not yet available, due to various standards and copyright-protection issues—and both allow you to record from their devices to a VCR.

THE PRIMARY DIFFERENCE between the two companies is that one—TiVo—collects data about your viewing habits, such as which shows or commercials you watch and for how long, and Replay does not. (This allows TiVo to charge slightly lower prices.) TiVo uploads your data every night during your unit’s dial-up connection for its program guide, then sells the aggregate data to programmers and advertisers. TiVo says that the information is also used to help determine your viewing preferences and thus suggest programs and advertising based on them. The company swears that any identifying information about you is never sent to advertisers—only statistics on the viewing habits of households in certain demographic categories.

Interestingly, the marketing of these units is reminiscent of that for K-Tel records or Ronco’s Instant Pasta Maker (Not sold in stores! Call before midnight tonight so you don’t forget!) You can order them through the companies’ Web sites or 800 numbers only. The reason? Both firms are trying to get TV, cable box, and VCR manufacturers to include this technology as an add-on feature in the next generation of video equipment—in other words, to make “smart” TVs and VCRs. (Indeed, Replay says you will see TVs and VCRs with its system included, just like Dolby Digital is in some audio equipment, in stores by late summer or early fall.) It’s that convergence thing that Bill Gates keeps talking about—only in reverse.