as for digital signing and or windows certification all that means is that Microsoft WHQL test team has tested and has passed the hardware and driver for use in what ever OS you are using(thats Windows Hardware Quality Lab or some such. the people that brought you the NT HCL and so forth.)
your driver DOES NOT NEED TO BE SIGNED OR CERTIFIED TO WORK! all it means is that it has not yet been tested and stamped with the MS WHQL seal of approval(yet).