Hello Stefano,
In theory you should be able to do this. What you will have to do is find out which contains the function to put the monitor into stand-by. I am guessing that would be in the driver for the video card or it could possibly be in the windows system dll.
Once you locate the correct library then you can use the call library function in LV. There is a good link to a walk through here on the dzone, just type 'external code' in to the search.
I hope this helps,
Doug
