If there's lag, it's probably the TV. A lot of TVs do some image processing that delays the picture; this is why games like Guitar Hero have calibration. My girlfriend's TV has a delay of 116 ms. See if your friend's TV has a "game mode" where it disables the video processing to eliminate lag.
Most games don't have poitner calibration as DK mentioned, so your movements may be exaggerated on a large TV. It's very easy to get used to though, because it's very precise, and you can always see the pointer move on the screen.