AutoTab

AutoTab is a very simple-to-use software application that you can configure to automatically cycle through all your active windows at a specific time interval, as well as to minimize all inactive windows.
It runs from the system tray area and doesn't contain any complicated options or configuration parameters, which means that it can be handled with ease by anyone.

Clear-cut setup and accessibility via the systray

Installing this utility is a swift task that shouldn't give you any trouble. Once launched, AutoTab creates an icon in the system tray area and sits there silently while running in the background, so it doesn't interrupt your normal PC activity by showing balloon messages.
It can become active or inactive by just double-clicking the tray icon, and its status can be noticed by the color of the icon (green for active, red for inactive).

Set the cycle time and minimize inactive windows

As far as configuration settings are concerned, you can specify the time for cycling through all active windows (in seconds), ask the tool to minimize any opened windows you're not using anymore, as well as to run at every Windows startup until further notice. An important aspect worth noting is that the app works regardless of whether the user is idle or not.

Evaluation and conclusion

Unsurprisingly, it left a small footprint on system resources throughout our testing, thanks to the fact that it needed low CPU and RAM to work properly. It didn't hang, crash or show any error dialogs. Although it hasn't been updated for a long time, it still works smoothly on newer Windows editions.
On the other hand, AutoTab features only a couple of basic options and doesn't have any advanced configuration properties for more experienced users. Nevertheless, you can test it for yourself, since it's free.