Theres really no solid answer for this one. Be careful to not use much liquid, as the screen is pourous. I suggest just using a soft, lint free dust cloth. Computer stores als make disposable wipes made to clean LCD and TFT displays.
If youre really pinching pennies and need to get some smudges off the screen, you may just try a little diluted cleaning solution (without harsh agents) on a cloth. Avoid spraying it directly on the display- just put some on the cloth and then use it.
System specs? Lets just get down to it people:
My penis is bigger than yours.