With new versions of these operating systems due out shortly, why doesn't both Microsoft and Apple SHOW some green leadership. This would be easy:
Defaulty settings should be to switch off (not blank or screen savers but switch off!) all monitors after 5 minutes of inactivity. Imagine the power savings if this was the standard! Screen savers should be eliminated from the OS, and a 20 minute turn-off is far too long and unnecessary.
A simple key-press (any key) or a mouse movement re-ignites the monitor instantly.
Personally I have mine set to 3 mins.
