Windows Experience index changed

When I first bought my Vista Home Premium Notebook it had a "Windows
Experience Index" score of 3.2, with the lowest sub-score being the 3D
business and gaming graphics performance score with all other sub-scores
being at least 4.0. Not surprising because it is an integrated video chipset.

Then about a month ago suddenly my Index Score dropped to 2.3 with the
lowest sub-score being the Desktop Aero Performance sub-score with my 3D
graphics now being 3.0, and the rest being still at least 4.0.

I know that driver updates can change the score so I went ahead and
reinstalled all of the origianl drivers off of my recovery partition and
reran the Experience Index to see if the scores changed back to what they
were when I got the Laptop. But nope, they were the same as the changed
scores.

Does anyone know if either, Microsoft has changed the way the Experience
Index scores existing hardware? (I know that they were to add higher scores
than the 5.9 that was the highest score possible when Vista Launched as new
technologies allowed for better performance). Or if when a new driver is
updated to a newer version it is updated on the recovery partition as well?
(I highly doubt this is the case as it would then not be restoring to
"factory defaults".)

Any help into this issue would be greatly appreciated,
piook
--
piook is a long standing psuedo-name that resulted from a typo on the old
computer game "Where in the USA IS Carmen Sandiego", and it stuck.