The other part of the HD equation is video, whether it comes through your cable box, satellite box or DVD player. Only shows and movies marked as HD will have the sharpness and clarity to get the most out of your TV. Standard-definition shows look worse on an HDTV, which just magnifies the graininess of non-HD video.

Expect to pay around $1,500 for a set with a decent quality 42-inch LCD (liquid crystal display) screen at a big consumer electronics store. As you go up in display size and price, sets with a plasma screen become a better choice for picture quality. On the other end of the scale, subtract as much as $700 for a smaller LCD or one with fewer features at a discount store. Rear-projection TVs give you a plasma-size display at LCD prices, but the image isn't great unless you are sitting pretty much in front of the set.

With less well known brands, ask your sales clerk about service after the TV's warranty ends. Some brands won't fix problems after one year; others charge you to ship your TV hundreds of miles for repair. Get answers in plain English.

Whether you're looking for the high end, low end or something in between, when you're HDTV shopping, here's what to know before you go:

1. Get a head start

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2. Figure out what will you watch on your TV. Plasma is great for sports and movies. The best LCDs are catching up, but plasma still wins, especially in contrast. LCDs are the best choice for avid gamers and for screen sizes 42 inches or smaller. What do you need to connect to your set? Make sure your new TV has enough inputs for your DVD player, video game system(s), cable or satellite box, VCR, computer, and has room to grow. Get a TV with at least two HDMI ports (your future DVD player will thank you). The more inputs the better, because devices that you don't even know you want will need to connect to your TV. But don't let the number of inputs become a deal-breaker; stay within your budget.

3. Look at your room. A well-lit living room will likely need an LCD, which doesn't reflect light. Darker rooms make plasma's superior picture quality really stand out. Your TV screen's size will determine furniture placement. How far back should the sofa go? Multiply the screen size in inches by 1.5 - that's the minimum distance in inches between TV set and sofa. Divide by 12 to convert your answer in feet. HDTV delivers the most impact when your eye level is at the center of the display, so budget money for a stand or a wall-mounting system that puts your TV at eye level when you're sitting on the couch.

4. Know your budget

Get familiar with the price ranges for HDTVs, and keep in mind you'll need to buy extras, such as a sound system, TV stand or wall-mounting hardware. It's not like the old days of buying a TV set, bringing it home and plugging it in.