As HDTV prices continue to drop, a lot of potential buyers are curious how HDTV really works. ProjectorCentral.com has a great article that explains HDTV in plain english. The article states:

So how many more scanlines do you get? Well, there are two popular HDTV formats in use. One is called 1080i, and the other is 720p. But don't worry, there are no format wars to worry about. All digital projectors and digital HDTVs take both formats. The fact is that ABC, ESPN, and Fox broadcast in 720p, while CBS, NBC, HDNet and others use 1080i. Both formats produce great pictures that are a leap forward over regular television.

Definitely an article you'll want to read before you take the HDTV plunge.

HDTV in Plain English