There are three kinds of laptops: the kind you buy as a second computer (usually small, light and expensive), the kind you buy to handle any possible computing function (large, often heavy and always expensive) and the kind you buy for basic chores like e-mail, Web browsing, writing and personal finance (still kinda large, still kinda heavy, not so expensive).

This issue focuses on the third kind -- the general-purpose, portable computer people buy when they don't want to splurge on lavish units with DVD players and 15-inch active-matrix screens. They probably don't need to tote the laptop on weekly flights to San Jose, but they do need to haul the computer around town or across campus. Or maybe they just don't want to devote an entire desk toward the care and feeding of one computer.

It's not that we don't like those other two categories. It's true that full-featured, "desktop replacement" laptops' prices have eroded -- from $6,000 and up to maybe $3,000. But that's still a big chunk of change to throw down when a desktop of equivalent performance costs less than half as much. And while we're intrigued by the newer sub-notebooks -- for instance, Sony's hot-selling Vaio 505 -- relying on one of these $2,000-plus, small-screen, small-keyboard contraptions as your only PC is less than practical. It doesn't help that almost every manufacturer with a sub-notebook sells the CD-ROM drive as an extra-cost peripheral; CD-ROM capability is only "optional" if you never install software.

We also keep hoping that the sub-sub-notebooks running Windows CE and other non-desktop operating systems will prove to be a decent laptop substitute, but they're just not there yet. Their keyboards are still a bit too small for extended touch-typing, their small screens become tedious to use and their $1,000-ish prices are a little too close to the costs of a "real" laptop.

So that leaves the kind of $1,300-$1,800 laptops, from such manufacturers as IBM, Compaq and Toshiba, that we describe here. (Last week, Apple unveiled its long-awaited iBook consumer laptop, which we will review as soon as we can get our hands on one.) With these, and with any laptop, a few rules apply:

*Never buy a laptop without looking at the screen. The best and priciest are active-matrix (aka TFT) displays; these offer contrast and brightness close to a traditional cathode-ray tube. Many low-cost portables, however, use dual-scan passive-matrix displays, which are cheaper, dimmer and a bit duller than active-matrix. ("High-performance addressing" screens close this gap somewhat, but not entirely.) Passive-matrix displays' slow refresh rates can also cause moving cursors to leave ghostly trails. That's unsuitable for games, but acceptable for most writing and Web work.

*Never buy a laptop without trying out its keyboard and pointing device. Laptops are by nature less comfortable to use than computers with separate keyboards and screens, so make sure you're comfortable with the placement of the keyboard and its key layout. If you haven't used either of the two prevailing mouse substitutes -- eraser-sized pointing sticks and small rectangular touchpads -- try both; most people seem to favor one and hate the other.

*If you do plan to haul the laptop around, get a feel for its weight. Check to see if you can't lower the travel weight by removing components such as floppy or CD-ROM drives.

*Finally, check the basic specifications. Any computer with less than 32 megabytes of memory and less than a four-gigabyte hard drive is underdressed, especially since upgrading a laptop's hard drive or memory is likely to be trickier and costlier than on a desktop. (A word on hard-drive sizes: Many companies, including all the ones reviewed here, define "gigabyte" as 1 billion bytes -- a convenient way to make a drive look roomier than it is, but also untrue. Win 98, the Mac OS and any computer-science student not looking to flunk use the correct figure, 1,073,741,824 bytes; we use that calculation as well.)

Join me for a discussion of laptop likes and dislikes, from noon to 1 p.m. today at http://www.washingtonpost.com/ffwd