I'll tell you how I do it if it's any help. But you will need to use a workstation or another system that has SSR installed beause the system will bog down considerably doing this and I'm not sure this program will install on a server. So if you have another system handy running XP\7 that you can copy some images too this should work.
I use this free open source program called Winmerge because unlike WinDiff it can compare drives and folders by size. http://winmerge.org/
It needs to be setup first by going to: Edit> options> compare then in the drop down box select "size"
Then I mount 2 recovery points at the same time as different drive letters. You want to select a "big" incremental and the one right before it.
Then click File > Open and select the 2 mounted drives, one on each side. After it runs you will see exactly what took up that space if new data was indeed added to the larger system image.
Best of luck
Dave
