Software. If you're serious about using a personal computer for more than just playing games, you'll probably spend at least $1,000 on hardware--you know: the computer itself, a television monitor, maybe even a disk drive or two and a printer.

Sometimes it can come as a shock that you still have to spend another $50 to $1,000 and up for the software you need just to get the darned thing to do what you want it to do.

Software's big business. I mean, in the billions. And the signs are all there that it's going to get bigger, with big-time literary agents vying to represent the best software writers and huge publishing houses buying up tiny software publishing companies like mad.

What they're all looking for are those rare winners that are so good that, after the user uses them a while, he or she stops thinking they're working with a computer and start to believe the computer really is a checkbook. Or a typewriter. Or a starship, if games are your bag.

Some of them are so extraordinary that they can end up transforming the user's life in ways that were never imagined by the man or woman who wrote the software.

One such piece of software is Howardsoft's Tax Preparer. It was designed for the mundane task of helping accountants and tax consultants with smallish businesses to quickly and easily prepare their clients' income tax returns.

But it ended up doing a bit more than that. In fact, quite a bit more: it has created a remarkable little cottage industry in which ordinary people have discovered that the Tax Preparer can transform them into neighborhood income tax whizzes and thereby earn them extra income.

"It's one of the biggest elements of our business now," says Dianne Prittie, marketing chief for the La Jolla, Calif. firm. "It never occurred to us that this would happen. But it did."

Of course, it's really a combination of things that is responsible. The drop in the price of computers is one. And the cheapness of the software package is another (it sells for between $200 and $250).

But most important is that Tax Preparer, like VisiCalc and the handful of others that have helped make personal computers part of the everyday scene in so short a time, is "user friendly."

That means someone quite ignorant about computers--like me--can buy it and a computer on which it runs and, within a couple of hours, be doing his or her own taxes in a fraction of the time it took before.

It's important to understand, however, that Tax Preparer and the dozen or so other income tax preparation software packages now being offered (they range in price from $50 to more than $1,000) are no substitute for professional tax advice. You still have to know what is depreciable and what isn't, otherwise you'll have Uncle Sam breathing down your neck.

But once you figure that out, the software will do the proper calculations and then enter them on the appropriate lines of the IRS 1040 form. It even has in its memory 20 IRS forms, including Form 2106 for employe business expenses, and Form 2441 for credit for child and dependent care expenses.

The Tax Preparer is a success because its documentation, the support offered purchasers by Howardsoft, and the software's user friendliness are excellent.

Documentation is nothing less than the software's instruction book. A good one is replete not only with examples and artists' illustrations of what the screen should look like when you do different things, but with simple, straightforward, no-nonsense instructions.

Lesson No. 1 when buying software: spend some time reading the instruction book. If you can't understand it, don't bother buying it. Otherwise, you're asking for trouble.

Customer support is the kind of response you get when you can't figure something out and you call the manufacturer. The more expensive the software, the more important it is. Lesson No. 2: If you're going to spend a lot of money, it might be worth a call to the manufacturer just to see how they treat you. Certainly, you ought to ask anyone you know who uses the software about the reputation of the manufacturer for being helpful after purchase.

As for user friendliness, you're only going to learn about that if you try it out. Hence, lesson No. 3: test the software in the store. Just about every computer store lets you do that, and if they don't, think twice about patronizing them. If it seems easy enough to run with lots of on-screen help, it's worth buying. It helps, too, if the sales personnel appear familiar with it.