Originally Posted by Ommid 
I have a western dig wd5000aaks and that gets 5.9 got 5,9 in my xps with the western digital too, but with a seagate it got like 5.4 or 5.2
As I have the same WD, I can only come to the conclusion that as others have said, the Vista BMs are useless. Actually from the speed with which they come up with numbers I don't think they are BMs at all, but some sort of database lookup. No doubt some scores are down to them incorrectly recognizing some parts.