- Computer Configuration > Policies > Administrative Templates > System > Power Management > Video and Display Settings > Turn Off the Display (Plugged In or On Battery)
There seems to be another setting which only applies to Windows Vista and above - "Turn Off Adaptive Display Timeout", which is pretty confusing based on the wording. Here is what I think it does: you know how sometimes, your screensaver or monitor just begin to shut off when those timeouts are hit, but you move the mouse real quick to stop that from happening? In that case, I have seen that even though the machine begins to activate the screensaver, lock the screen, or shut off the monitor, you can sort of "catch it" before it finishes and it lets you right back in. That's the adaptive part - the system detects this condition where you just about timeout but catches it before it finishes happening. Based on how much this happens to you, Windows automatically adjusts the Display timeout value to try to prevent timeouts from being annoying.
The group policy wording states: "When this policy is enabled, Windows automatically adjusts the setting based on what users do with their keyboard or mouse to keep the display on. When this policy is disabled, Windows uses the same setting regardless of users’ keyboard or mouse behavior. If you don’t configure this setting, users can see and change this setting.". It's confusing because they say "Turn Off" is "enabled" - but I think what they mean is, the adaptive timeout for turning off the display policy is enabled or disabled. That makes more sense to me at least. I will test it and see what happens.
There is also nice post over on the Microsoft Directory Services team blog that discusses other power management options with AD.