In most cases, yes. The story I always tell is of my first experience seeing HDTV. I was watching a Penn State football game, the camera zoom in on the quarter back and you could see the hairs on his arm. You won’t see that kind of detail on TV or DVD.  If your DVD player has built in up-converting circuitry, that’s where your DVD player with it’s 480p of res can digitally enhances it to near 720p, you’ll see a mush sharper image although still not of the quality of HDTV.

Keep in mind, just because you have an HDTV, that doesn’t mean you will see everything in High Depth. You need to be watching a  channel that is in broadcasting in HD. Not all channels are currently sending a true HD signal.