Has anyone noticed a slight bit of lag when playing Xbox (or PS2/Gamecube) on a LCD HDTV? I've heard that it has something to do when the TV needing to upscale the picture to its native resolution (something that shouldn;t be a problem with the next gen consoles that output at 720p).
If you are running the game through a VCR or other inline device, this can cause the lag too. Plug it directly into the sets inputs and this should handle it I find.