(MONEY Magazine) – Don't look now, but the personal computer is shrinking. In recent months, four PC makers -- Atari, NEC, Poqet and Zenith -- introduced mini-machines, known as notebook computers, that are even teenier than laptops. Unlike the laptops, which are actually a bit of a handful at 10 to 16 pounds, the notebooks are truly totable, weighing in at one to 5.9 pounds. They go for as low as $399.95 or as much as $2,999 vs. $999 to $3,699 for the laptops. The smallest notebook is the Poqet, which, at 8.75 inches by 4.3 inches, will literally fit in your palm. Minuscule as they look, notebooks can pack the word-processing and spreadsheet capabilities of a desktop and allow you to transfer files into other computers. So who needs one? The notebooks are worth a look if you could use a traveling machine to back up a conventional PC at home or in your office. Otherwise, your eyes and patience could easily tire from the notebook's miniaturized screen and batteries, which in some cases burn out in two hours. ) Also, don't expect any of the notebook computers to feel exactly like a desk-top, advises Andrew Seybold, the Santa Clara, Calif. publisher of the monthly newsletter Outlook on Professional Computing. For example, notebooks typically will not use floppy disks, which you may already own. Instead, they conserve space and power by using ROM cards for word processing and spreadsheet applications. A brief rundown of the souls of four of the new mini-machines: -- Atari Portfolio (suggested retail price: $399.95; weight: one pound). This, the least expensive notebook, uses three AA batteries that last for 80 hours. But its 320-character screen is by far the most constricted of the four, barely able to hold a 40-word paragraph of text. And Chiclet-type rubber keys make touch-typing impossible. The Portfolio comes equipped with basic word- processing and Lotus-like spreadsheet software as well as a calculator, diary and address book. It best suits people who want day organizers with computing power. -- Poqet ($1,995; one pound). The newest and frailest notebook comes from the developer of Texas Instruments' Speak & Spell machines for kids. It's MS-DOS compatible, runs on AA batteries for 80 hours and has built-in word-processing software as well as a calculator, appointment scheduler and address book. Poqet runs Lotus 1-2-3, but you must buy separate software that costs $495. One other drawback: you may need extra-strong glasses to read the Poqet text, which is tinier than what you're reading here. The Poqet is recommended for people who think small is all. -- NEC UltraLite (two models: $2,499 and $2,999; 4.4 pounds). The UltraLite has a lot to offer, including a built-in modem and laptop-size keyboard. But it has a major hitch: though the most expensive notebook, it runs for only two hours before requiring a seven-hour recharging. UltraLite is most attractive for people looking for speedy calculations. -- Zenith MinisPort (two models: $1,999 and $2,799; 5.9 pounds). Computer reviewers complain that the MinisPort screen isn't very bright. And its 12- volt battery lasts only about 2 1/2 hours. An optional replaceable battery can double that time, however. This machine is worth considering if you want a small personal computer for long trips.