The Audioholics story ticks off six things you need to know before you buy an HDTV, and it's a must-read if you're in the market for your first high-def set. Here's a brief summary of some of the pointers, along with some thoughts of my own:

Your new HDTV needs an HD feed: Just plugging your regular cable or satellite box into your new HD set won't get you a high-def picture. You'll need to contact your cable or satellite provider and ask for an HD set-top box (satellite subscribers may also have to upgrade their dishes), and you may want to sign up for an HD subscription plan, as well (which typically offer channels like Discovery HD Theater and HDNet). Still watching TV using an over-the-air antenna? A good, properly aligned rooftop antenna may still do a good job of pulling down HD signals, but unless your HDTV has a built-in HD tuner (many don't), you'll have to buy a separate high-def tuner box to go with your set.

Your HDTV/set-top box/cables must be configured properly: First, make sure you're using the right inputs when connecting your HD set-top box to your HDTV. You must use either the component-video inputs (a trio of RCA-type plugs, marked "Y," "Pb," and "Pr") the DVI input or the HDMI input. The composite and S-Video connectors on your TV can't receive HD signals, so if the cable guy starts hooking those inputs up, time to raise the red flag. Also, your cable or satellite HD box must be set to send an HD signal to your display; go to the set-top box menu and look for the display settings, and select either 720p or 1080i (depending on the native resolution of your HDTV). Finally, once you're ready to watch HD, make sure you're watching the right channel. If you're used to watching ABC on, say, cable channel 7, that's only the standard-def version of ABC; the HD version is probably much further down the dial, usually in the 700s. Check your programming guide.

Most TV programming is still in standard definition: I'm still amazed by how many people think that an HDTV will display all their shows in high definition. Now, if you're only watching scripted (i.e., non-reality) prime-time shows on the major broadcast networks, then yes, there's a good chance that most of those shows are in HD (save a few holdouts, like "Scrubs" on NBC). But the vast majority of programming that's out there, ranging from "Queer Eye" and "Regis and Kelly" to "Pardon the Interruption" and "Sesame Street", is produced in standard definition, and your HDTV won't magically convert SD shows to HD. Check out TitanTV to see what's in HD in your area.

SD typically looks terrible on an HDTV: Standard-def shows can look remarkably bad on a 50-inch display. Imagine taking a grainy Polaroid picture and blowing it up to monster size. If you miss how CNN used to look on your old 27-inch direct-view set, keep in mind that you were watching it on a much smaller screen.

HDTV screens are wider than SD pictures: Because HDTV screens have a wide 16:9 aspect ratio, your new set will stretch the boxy 4:3 shape of a standard-definition show to fill the screen, which will make everything look short and squat. You have two choices: either live with the short-and-squat look on your SD channels, or dig into your HD set-top box settings and add sidebars to the SD channels. Yes, you'll have to deal with black bars on the left and right sides of the screen, but at least the picture won't look like a circus fun-house mirror.

An upconverting DVD player doesn't turn standard DVDs into HD: I'm a big fan of DVD players that upconvert standard-def DVDs to 1080i or even 1080p, but make no mistake; because the source DVD disc is standard definition, you're still watching an SD picture (albeit, one that's been extrapolated to HD proportions). If you want true HD images from your DVD player, you'll have to pony up $400 or more for a Blu-ray or HD DVD drive.