DON'T use glass cleaner!! You can buy chemicals just for monitors and LCDs
at most computer stores. A lighly damp cloth (water) will also do the trick
if you do it often.
Windex and similar wear off a film that covers the screen over time and will
pretty much destroy your display.
At work, we use "Free of Charge" mfg by rubachem http://www.rubachem.com/site/index.html. Since they are free of charge, I
sometimes bring a couple home from work to use on my personal laptop ;-)