Perhaps the most common mistake made by those purchasing HDTVs is the assumption that an HDTV will automatically receive HD content. The world would be a nicer place if that were true, it is not. To display HD content, your HDTV needs to receive an HDTV signal. That means a signal which has a resolution of at least 720p. An HDTV can certainly display older, 480p television, but it doesn't look any better than on an older tube set.
The major over-the-air channels in America and other countries do broadcast an HD signal over the air. Yes, that's right - it is possible to receive full HD over a set of bunny ears. Cable channels and satellite channels, however, continue to be mostly broadcasted in 480p. To gain access to HD channels you need to sign up for their HD service. Which, wouldn't you know, costs more.
If you want to watch movies in HD then you will need an HD-DVD or Blu-Ray player and some movies which are in those formats. HD-DVD is discontinued, but players and movies can be had at bargain prices. Blu-Ray, on the other hand, still commands a price premium. New Blu-Ray movies often cost thirty dollars, and even the most basic players cost around $200 bucks. That said, those who will simply be using regular DVDs will be in for a surprise. While standard DVDs are not recorded at HD resolutions, there are numerous players capable of upscaling a DVD. This essentially means that the player has a special processor meant to turn the lower resolution DVD image into a high resolution image displayed at up to 1080p. The best upscaling players are so good that it can be sometimes difficult to tell the difference between an upscaled DVD and a Blu-Ray disc.
Make sure that you plan to buy at least one method of receiving an HD signal before purchasing an HDTV. Many have purchased their new set only to find that they could not enjoy it without spending more on a Blu-Ray player or better cable service.
That's the basics. At this point you should have an understanding of what the term HDTV means, what is important to you in an HDTV, and how you will feed your new HDTV an HD signal. With those bases covers, its time to start examining the actual televisions. The next article in this series will talk about the big question on every HDTV buyer's mind: LCD or Plasma?