No, you don't. While HDTVs with 1080p resolution are becoming
more common, especially among big-screen rear projectors and flat-panel LCDs, you don't need a 1080p HDTV to get the most out of your high-def investment.
The advantage of 1080p native resolution, which just means that the TV has 1,920x1,080 pixels, is that it allows the display to put every detail of 1080i and 1080p sources on the screen at once. HDTVs with lower resolution don't display quite as much detail, but the real question is: Will you notice the difference? In truth, most people will have a hard time distinguishing between a 1080p HDTV and one with lower resolution (typically 1,280x720 or 1,366x768) regardless of the source quality or even the screen size.
But if you want the best you can get today, and you don't mind paying more for it, then you should probably consider going 1080p. That's especially true if you're getting a very large HDTV, say 56 inches and up, or if you plan to sit relatively close to the screen, say 1.5 to 2 times the diagonal measurement. Typically, 1080p HDTVs, especially flat LCDs, are better at displaying computer sources than their lower-resolution brethren. Most non-1080p HDTVs are perfectly suitable in these situations as well, however.
Note that we're talking about 1080p native resolution only in regard to a given display's pixel count. The resolution of the source, such as a Blu-ray player that outputs at 1080p, is a separate matter