If you want some programs to run while you are away, but don't want to disable the power saving functions of Windows, Stims could be just what you are looking for. It runs subtly in the tray and can prevent the computer shutting down due to inactivity for a selectable period from 30 minutes to 2 days. It can also be locked on. Stims can be set to simply prevent shutdowns, or it can make the computer think someone is active by simulating a button press every minute. Stims can also be activated via the command line, and can be set to auto-start with Windows and/or automatically close when the Stims run out.