Hello, A friend of mine just purchased the Sony HP51W40 and is considering an ISF calibration. She is by no means a videophile, but wants to get the most out of her set. If she gets the calibration done, will the 4 year warranty she bought be useless? Tweeter recommended against the calibration because of this. Also, since she is not a videophile, will the differences in picture quality be worth the $300+ it will cost to have the calibration done? What differences can she exepect to see once the calibration is complete? Thanks in advance.