You can't shop for a TV set or audio components anymore without running into the concept of "home theater." A home-theater system is supposed to make watching TV a little more like going to the movies.

These systems no longer are just for audiophiles and film buffs. The Dolby sound tracks needed for the home-theater "surround" effect have become more common -- found not only on videotape movies but on a growing number of TV programs. Dolby Pro Logic receivers that can decode Dolby sound tracks have dropped in price. So have TV sets with large screens, the centerpiece of most home-theater setups; some 27-inch sets cost as little as $340. And the audio components of a home-theater system are increasingly sold in packages.

In a full home-theater system, the receiver (or, in a few cases, the TV set or a stand-alone decoder) processes the sound track and then plays it through five carefully placed speakers. The result is a decent re-creation of the three-dimensional effect you hear at your local movie house.

The components of a full home-theater system will generally cost at least $1,500, not including the TV set. Also, the system will take up space in your living room, and can be a headache to wire together.

Though generally less powerful and less flexible than component systems, packaged audio systems promise to make home theater simpler and more compact. For $400 and up, you can buy a "home-theater-in-a-box" -- usually five speakers and a Pro Logic amplifier that connect with a TV set or VCR. If you need other audio components (and often more power), you can move up to Pro Logic mini systems ($700 to $1,000) or rack stereo systems ($1,000 to $1,500).

You need:

Front speakers. The left and right front speakers produce most of a home theater's sound, and should be the best quality you can afford. Front speakers should sit to either side of the TV set, far enough apart to produce a noticeable stereo effect -- ideally, the two speakers and the listener should form an equilateral triangle.

Surround speakers. Because they'll handle only ambient sounds, these can be smaller and lower in quality than the front speakers. Surround speakers should be positioned toward the rear of the room, high up (mounted to the wall, if practical) and pointed away from the listener. This increases reflected sound, and so enhances the "surround" effect.

Receiver. Unless you buy an expensive TV set that has Pro Logic circuitry, your home-theater system will require a Pro Logic receiver -- with at least 65 watts per channel to provide window-rattling explosions and ear-splitting tire screeches.

Center speaker. A home-theater system sounds best if you run its center channel through a center speaker. Because it will be placed just above or below the TV set, the center speaker must be magnetically shielded so as not to interfere with the TV set's picture.

TV set. Your present TV set may well suffice. The set need not have fancy sound, since you'll probably bypass its speakers. (However, in order to do that, the set must have audio output jacks or you must also own a hi-fi VCR.) And your TV set need not be huge. The "surround" effect can be created even in a small room, provided the speakers are placed correctly.

VCR. Only a VCR with stereo "hi-fi" capability will do. If you don't own a hi-fi VCR, the good news is that models with good picture quality now cost as little as $270.