“I have a 250GB hard drive. When I look at the properties of the drive, it tells me that I have 75GB free and that 175GB are in use. However, when I add all my files together, I only see 150GB in use. That is a difference of 25GB. Where did my space go?”

Ever have a similar question in your mind?  Sure you do.  Robert explains many of the mysteries in the blog post at http://blogs.technet.com/b/askcore/archive/2013/03/01/where-did-my-space-go.aspx.  Nicely done Robert.