J.L.
You can use window cleaner but don't spray it onto the screen, spray onto a SOFT cloth (not paper towel) and then wipe the screen. The best stuff I have found though is the glass cleaner from the Walmart Vision Center - it is for no glare glasses and works great for the monitor - same thing though - don't spray directly onto the screen.
I should have specified to use window cleaner without amonia as that is what will ruin the screen (I worked in the IT Dept for a school district for 3years). That is why the cleaner from walmart vision is best but my regular window cleaner is also amonia free (can't breathe around that smell).
It really ends up being a matter of opinion. For example, one doctor may say that one glass of wine occassionaly while pregnant will do no harm while another will tell you to NEVER do it. :-) Take all the advice you get and decide what feels right to you. Have a great day!