USBasp from obdev is general development plateform for electronics enthusistic to start development with usb functionalities .
the driver of usbasp is published under general utilisation. In earlier versions of windows one can utilise this drivers and inf to work with MFC(Microsoft windows classes and framework).In windows 7 unauthorised drivers cannot be worked as in stop permitting any unauthorise resources such as obdev to install their drivers into system folders and let them to register under registry .This access is blocked in order to protect users from virus attacks and malwares..OVERALL one can use driver signature overrider software to stop blocking winodws and let the usbasp to work with it.
Note: Windows Vista/7 x64 requires drivers with digital signature. Currently there are no official drivers for libusb (USBasp software is based on it) with such a signature. Users reported that there is a tool named “Driver Signature Enforcement Overrider” to avoid the signature check
download link
http://www.ngohq.com/home.php?page=dseo.