Lost drive space in Windows XP

The issue I am dealing with is a user of mine has a new Lenovo laptop with 100 GB hard drive.  We have Windows XP Pro SP2 on it, and VMWare Workstation running on it.  He installed a VMWare image from a software vendor that used up over 35 GB of space.  He corrupted the VMWare image somehow, and decided to delete the root directory where the image was.  Of course, being the size it was, it proceeded to permanently delete the entire folder - which is what we wanted.  Anyway, the folder is gone, the space is still not available.  I have checked sizes on all folders (yes, even the recycle bin) and made sure I was not hiding any system files.  The total of the space being used is no where near the drive capacity, and does not add up - there is 35 GB missing still.  I have know idea what to do at this point, and would prefer to resolve with a drive tool rather than re-formatting and reinstalling.  I appreciate all assistance!