Remember HDTV lag come from upscaling. So if you want to play ps3 and 360 games on this HDTV since most games run at 720p then you should have no problem with lag. (with wii,ps2 or older you may experience lag) Some HDTV can upscale better than others as well as some upscale a little faster. Mostly good upscalers are design with DVD movies in mind where exact timing isn't an issue unlike games like GH3.
Some HDTV like Sharp Aquos has a "game mode" option where it will upscale as fast as possible yet of course doesn't try to smooth out those "double pixels" so the image can be a little rough. Since all but CRT HDTV have fixed pixels in order to upscale the image to it's native resolution some pixels have to be double up while others are not. HDTV tries (as well as upscale DVD players) to blend in these double pixels so they are not as noticeable which improves the image quality but requires time to process the image.
