Space available: different result between Property and JDiskReport



I have just checked my available space in C:
Property shows I am occupying 90.6 GB (and oddly it "steals" some GB
while Vista is running and my hard disk seems to fill up by itself.
JDiskReport shows I am using only 85.8 GB and it provides a detailed
list of my files.
Who is it right?

My Computer