Assuming you are using a desktop system the best you can do is shut down the computer, thus the monitor will go to stand by. The only way to switch off the monitor completely is by physically using the on/off switch on the monitor. Sorry.
Thanks for the response. That seems to be correct for the 2 19" Flat Panel Dell's I have, but I just purchased a 17" Flat Panel Gem for my 3rd Computer, and it shut's off automatically after the CPU shuts down. Seem's the cheapy works better than the Dell's at 2 to 3 times the price.