Until now, the USBASP windows driver wasn’t signed. On older versions of windows this was’t too much of a problem as you could override the signature error. On Windows Vista x64 and Windows 7, it is almost a show stopper.
Various methods have been suggested including a utility called Driver Signature Enforcement Overrider or Pressing F8 at boot time and selecting Disable Driver Signature Enforcement. These approaches were far from ideal.
With the release of libusb-win32 version 188.8.131.52 this is a thing of the past. A new USBASP driver is now available; is based on the libusb-win32 driver; and supports 32 and 64 bit windows. It is partially signed which means windows still produces a warning during installation, but that warning does not prevent installation of the driver.
OK, now for the installation procedure…