@Peter
There currently is no password screen at all, timed or not (besides login to AC). Since I would not think staff would be your main worry (because they have access to AC already) I would simply configure screen savers on a timer through Windows with the "On resume, password protect" box checked. Make sure that all user accounts have passwords and don't allow use of the normal login screen, instead require the username entry. That should be sufficient password protection for most. Now if you are walking away from your computer you can also press the Windows key+L for a quick screen lock.
