Here is a freeware utility called MK Autorun Disabler which allows you to enable or disable all drives autorun in windows in single click. Thus this small utility will prevent virus attacks due to autorun viruses in your removable USB drives. MK Autorun Disabler is a clean tool (Tested with Nod 32, do check it with your own) and can be downloaded from here. It works with Windows XP/Vista/7.