Running Vista Premium Home on a 500 GB hard drive shows 80 GB used in
properties pie chart. I configured win explorer to not hide system files,
actually see hidden & system files in directories.

If I get properties of the root & all folders, their sum is about 18 GB.

How can I account for the 4X overhead shown in the pie chart? Why does the
sum of the folders disagree so much with the pie chart?

In running a ghost image, the ghost size is about 60 GB, which is in line
with the 80 GB pie chart. Why do you think I only see 18 GB?