i tried to calibrate my laptop screen a while back. needless to say the outcome was i got an old crt to use instead, and then bought a desktop pc. the main problem was that any calibration was only valid for the part of the screen directly perpendicularly in front of me, otherwise it was all over the place. this was a couple of years ago though, i expect laptop screens are better now. the other problem was that all the contrast etc that you want to fuck with were controlled via software rather than twiddling knobs, and it was hard nay impossible to get the screen driver to not fuck with the calibration of it own accord some how. i probbaly just had bad luck though!