If you don't know a burn-in from a black black, your TV is probably stuck in the last century.

It took three months of investigation to decide which type of flat-screen television was best for us, picking up some new vocabulary on the way: "refresh rate," "screen performance" and "black blacks." You may want to study our findings before you begin your own shopping trip.

There are two major types of flat screens: Plasma and LCD. Here are a few key differences:

LIGHTING

When we were first compared them side-by-side, it was immediately apparent that the plasma screen offered a much crisper picture. The image seemed slightly sharper, the blacks were blacker (a higher contrast image) and thus, the colors were more vivid. But the LCD picture seemed "brighter," and it was easier to see detail in highlights and shadows from almost anywhere in the room.

We were soon to learn that each of the two types had advantages. For example: where the plasma had a sharper image and brighter colors, room light and outside light reflecting off the highly polished screen made it difficult to see the picture from any angle. And where the LCD picture was slightly muted and not as sharp, we could see fine detail in shadows and highlights even in a brightly lighted room.

That means the LCD is perfect for use in rooms filled with windows. The screen is back-lighted which nullifies reflection of ambient light. On the other hand, a plasma screen, placed in a room where windows could be completely shaded, offered the very finest picture by far.

ACTION

Because the image on plasma screen refreshes more quickly than an LCD, action on a plasma screen is far more realistic. This can be important if you are a sports fan. On an LCD screen, a football flying through the air is usually followed by a ghost image. No ghost image on a plasma screen.

PLASMA PROBLEMS

In a controlled environment the plasma is sharper, provides more brilliant colors, offers greater detail and doesn't have ghost images. So what's the down side? Most important is price. A plasma screen television is literally double or more an LCD's price.

But there are other problems: The screen's lasting quality is poor, with about a six year life span with average use. The condition that shortens the life of a plasma screen is known as "burn-in." This is where a still picture can burn an image of itself into the screen.

Handling is another problem. Plasma screen televisions are much heavier than LCD units and are less portable and more difficult to move. The experts say that plasma TVs are more fragile and less sturdy as well. Finally, plasma TVs tend to become very hot when in use, which requires careful planning for locating and mounting.