This is what I see when I have a look at the disk management:

As you can see the capacity of Volume 2 is all over the place. 931GB is what I was expecting so it was a bit of surprise to see 723GB as well. I'm guessing it's a windows problem rather than a disk problem given the difference and the fact that windows 7 sees the full capacity in at least one location.
Any advice?
Cheers,
Chris