On Windows XP, the following command in a script will prevent any power saving options from being enabled on the PC (monitor sleep, HD sleep, etc.). This is useful for kiosk applications.
powercfg.exe /setactive presentation
What is the equivalent on Vista?
powercfg.exe works a little differently in Vista, and the "presentation" profile isn't included by default (at least on my machine. so you can setup a "presentation" profile and then use the following to get the GUID
and the following to set it to that GUID:
Alternatively, you can use powercfg.exe with the -change or -X to change specific parameters on the current power scheme.
Snippet from "powercfg.exe /?":