Barricade

System Barricade prevents programs from harming your system by only granting access to the lowest privilege levels allowed in Microsoft Windows. Barricaded programs cannot write to your Microsoft Windows Operating System, and provide you with the knowledge that your system will not be harmed by questionable applications. The installation adds a context menu to all executable files, allowing you to run them safely. You just right click on the executable file in Explorer, and select "Barricade" and for this application instance the program has very limited system access.

Limitations:

Nag screen