Hi superbill,
It seems that 7 scores your HD on size, age and if it's a SSD or not.... I'm running a RAID 0 set up which has a burst speed of over 350MB/s and an average read of 120MB/s, so not slow... I get a score of 3!
I've noticed though that users running a single HD set-up (say 500GB will score higher than me although the drive will be a lot slower.. The only difference being is that the drive was a lot newer than mine.. Also like I said, windows 7 is more optimised to use SSD's than vista..
The 7 forums also have a couple of threads on this