"Hertz" is the number of times an image on the HDTV get updated per second. So if the TV you're shopping for is 120Hz, that means, the image is getting refreshed 120 times a second. The LCD's you listed only have 60hz refresh rate, which means they refresh 60 times a second. Although that seems like a lot, compare it to the Panasonic or Samsung plasmas that are 600hz. Just go see for yourself and watch a fast moving picture on the LCD, you'll see thats its all pixelated or choppy.