HD ready means it can accepts 720p/1080i signal. 100Hz is only line doubler. HD is useless? if your usage of the tv is only to watch terrestrial and astro broadcast then yeah it's useless. but if you want to use later for xbox360/ps3, best to get HD. if you got xbox1 and component cable + matrix: path of neo game, try hook it up at any HD tv and see how much difference HD picture quality can be. or ps2 and component cable + gt4, see how amazing the car look when racing.