A mind is a terrible thing to shake. So you might want to swaddle your noggin with a couple of futons before booting up Guide, the revolutionary software that can't think straight.

But then, neither can we -- especially when we read. Our thoughts slip askew; we muse on associated ideas, pause at unknown concepts, skip the obvious, demand more detail here, less there. And that, the program's creators say, is the problem with traditional printed prose: The exposition is obstinately linear, the topics arrayed in an inflexible hierarchy, the reader forced to be passive as a pothole. It's like telling a fish to swim in a straight line.

But suppose you could create a document so flexible that when the reader bumped into an unfamiliar term, he could just poke a key and a definition would pop onto the page. Or he could jump to cross-referenced material in the current document or even in another one, see a concept expanded, explore a related idea or call up a graphic display.

You could call it "hypertext." OWL International does, and its Guide program for IBM ($199.95) and Macintosh ($134.95) systems performs all the above and gobs more. Provided, of course, that you've got the now-standard gizmo inventory: a graphics-quality monitor; a mouse; and, for PCs, a copy of Windows, Microsoft's ungainly sluggard of an "operating environment" (included with purchase) under which Guide runs.

Guide documents are designed to be read on screen. They look superficially like any others, except that certain words and phrases stand out, marked by different typefaces. OWL calls these "buttons"; and when you move the cursor onto them and click the mouse, they perform one of four functions: 1) Replacement buttons fill the screen with new text, graphics, both, and/or more buttons. 2) Inquiry buttons offer menus of mutually exclusive options: "Choose #1 if by land, #2 if by sea." 3) Reference buttons whisk the user to a related point in the current or another document. 4) Note buttons display annotations in pop-up windows. What with the brain-boggling potential for multiple layers of buttons, a reader could get lost in the labyrinth; happily, there's a "backtrack" function.

Better yet, graphic images can serve as buttons: Each state in a regional map can call up a sales summary for that state; each section of a carburetor can bring up an exploded view of that part. You can make the text larger or smaller, search for specific words, link notes to definitions and vice versa, and "nest" options within options within options until your head feels like it's been packed with Prune Whip.

Guide makes the perfect training aid or library system for users of every ability. It lets scientists avoid marketing material and accountants pass over technical specs; yet both can append comments. Use it to brainstorm ideas, write interactive fiction ("Lance Hunter opened the door to find: (A) a mysterious jeweled coffer OR (B) two car-hop waitresses and a six-pack"), develop a personal file system with whatever nutball cross-referencing relationships you prefer.

And hold onto your dentures: It's about to be improved. Version 2.0, due in late October, will feature an additional button that allows the user to jump into some other program from within Guide (to run, say, animation sequences) and numerous other doodads. Cheapo upgrades will be offered to registered users. (OWL International Inc., 14218 NE 21st St., Bellevue, Wash. 98007, {206} 747-3203.)

Oy and damnation: You've been given 24 hours to find a sure-fire promo slogan for the client's latest product: A battery-powered, solid-state hog-caller. Never mind that Cheryl Tiegs, P.T. Barnum and the Singing Nun working together couldn't move this calamity. You've got Headliner, the new software phrasemaker and jingle-generator.

Headliner ($99.95 for IBM systems) is based, the publisher explains without apparent shame, on "an effective yet simple procedure: Find and modify clever or already popular expressions" to flack your widget. Just pick a couple key words (like dog), and tell the program to find all the dog phrases and substitute hog instead. That's no inconsiderable chore, since the options menu lets you choose among more than 33,000 phrases in 25 different databases, from song and movie titles to ad and marketing mottos to common idioms and proverbs. In seconds, Headliner burbs up "Hog Day Afternoon," "Hot Diggety Hog," "Putting on the Hog" and a score of other, equally mellifluous utterances. Use 'em as is, mix and match, or let 'em inspire your own porcine poesy.

Need more? There are seven search modes that will scavenge the databases for expressions that rhyme with, are similar to, sound like or elsewise embody your search choices. You can even restrict the output to a maximum word or character length. Want an acronymic phrase? Pick CAT for the letters and Headliner scrounges up "Catch a Thief," "Climb a Tree," "Carry a Torch" and so forth. Or select Profanity mode and have your final slogan checked for inadvertent smut in both English and Spanish. But watch out: Our word-slime specialist created half a dozen mightily unyummy epithets that Headliner okayed. Then get out there and sell it like it is. (Salinon Corp., 7430 Greenville Ave., Dallas, Tex. 75231, {214} 692-9091.)

Of all the things you can do with a computer, nothing is more universally infuriating than sending and receiving files by modem (the cybernetic equivalent of the bull terrier). Even if you succeed in hooking the thing up right, it can still take longer to "download" a two-page letter than it does to clean the attic. But now Hayes, maker of the legendary SmartModem, has released the V-Series modems, at 2400 or 9600 bits per second (bps) in external ($899/$1,299) or internal ($849/$1,199) models. Both do all the customary tricks your software demands. In addition, they have their own data-compression routines built right into the chips, effectively doubling the rated transmission speed.

As soon as you dial a remote computer, the new modem starts snuffling around to see if there's another V-Series at the other end. If so, the units automatically adjust themselves for maximum speed and start blathering away like two DAR matrons discovering one another on adjacent park benches. The results are amazing. We downloaded a big program file with an old Hayes modem at 2400 bps in 17 minutes. But when we hooked up a V-Series to each end, and called the same PC on the same phone number at the same speed, transmitting the same file took only nine minutes -- an effective speed of about 4400 bps. That's eight minutes' worth of long-distance charges and human down-time saved. Not to mention the cost in worry over dirty-phone-line errors: The V-Series doesn't care if there's a UFO convention perched on your wires. The built-in error-checking will probably get your data through.

You say you've already ponied up hundreds for a pre-V Hayes? Stifle that tantrum: For $349, you can get an Enhancer, which adds all the new features to your 1200 or 2400 external unit. Warning: You may experience neuro-gridlock while trying to reset your current software to take advantage of the Enhancer. Hayes manuals read like NORAD directives and the modems' configuration syntax is screwier than Canadian zip codes. Why Hayes has never written a plain-English set-up brochure usable by ordinary mortals is a depressing mystery.

Fortunately, the company's just-published Smartcom III modem software ($249 for IBM) does everything for you automatically. If you've tried a previous version of the program, look again. The display interface -- formerly a hopeless bow-wow -- has been completely rewritten, and now offers a handsome set of pop-up menu boxes, wads of on-screen help and thoughtful features like a "progress" window that tells you how your connection (or connections -- you can have two calls going at once, and switch between them with a keystroke) is doing. There's a good text editor and multifunction DOS shell, a "peruse" buffer that captures all incoming data and lets you save all or portions of it to disk after you've hung up, and a common-sensical "script" language for automating log-on sequences and so forth. There's also a nitwit idea or two, like the way each call requires you to specify both an "activity" and a "connection," a confusing distinction entirely irrelevant to most users. Still, if you move a lot of data over the phone, the modem-software duo will probably pay for itself before you can say "post-divestiture surcharge." (Hayes Microcomputer Products Inc., 705 Westech Dr., Norcross, Ga. 30092, {404} 449-8791.)

And while you're at it, you'll get a kick out of PhoneBoot. Sounds like a telephonic tea cozy; but in fact it's the best idea in out-of-town help since the au pair girl, and virtually indispensable for the itinerant computerite.

Say you're 2,000 miles away in West Dewlap, and you discover you've left your most important files back on K Street. Sure, you can use your laptop to dial up the office. But your home-base computer is turned off. If you're self-employed, you're suddenly in very deep sludge. And even if you've got coworkers to call, do you really want those hyenas rooting around in your files (including your secret plan to get old Beasley transferred to the Motor Pool)?

If the answer is no, you need this $329 unit the size of an egg carton. Before you leave town, just plug your office PC and modem into one of PhoneBoot's six outlets, connect the unit to a phone line, and flip the switch to "Code." Then take off. When you need to dip into your home computer, just dial the number. After eight or nine rings -- to eliminate chance calls -- PhoneBoot picks up the phone and tootles hello. Type your three-digit access code; PhoneBoot makes a ghastly squawk and fires up your PC. Connect by modem and you're (literally) in business. Eighteen minutes after you sign off, PhoneBoot shuts down the access code and goes back to waiting patiently. (Cybex Corp., 1860-B Sparkman Dr., Huntsville, Ala. 35816, {205} 830-1100.)

Sure, it's a few bucks. But you saved a bundle by buying an IBM "clone," right? You can see that from the keyboard. Did you get one made in some no-name Asian sweatshop, the kind that feels as though you're typing on macaroons and makes a sound like a bag of bottlecaps? Then betake your degraded digits pronto to Northgate Computer Systems' C/T ("click-tactile") keyboards in the Enhanced 101-key model ($99 with separate cursor-control, screen-control and numeric keypads) or the (yech) "standard" 84-key version at $79. Either way, they'll throw a party for your paws.

Unlike other after-market keyboards, NCS uses the Alps Keyswitches with a long-stroke travel and two-stage action. The result is a much more positive feel and a likely increase in speed, especially for touch typists who pace themselves by that kind of tactile feedback. And for ear-cued types, the C/T's audible "ping" is easily adjustable. Our typist-tester used one for two weeks and soon preferred it to her beloved Leading Edge (a true oxymoron), though she felt the cursor pad was too far away from the alphabet keys for efficiency and too near the edge of the case for comfort. Try it yourself; the sensation is sensational and the price is better than right. (Northgate Computer Systems, 2905 Northwest Blvd., Suite 250, Plymouth, Minn. 55441, {800} 328-8907.