Freeware Descriptions:
TreeSize tells you where precious disk space has gone to. It can be started from the context menu of a folder or drive and shows you the size of this folder, including its subfolders. Each folder can be expanded in Explorer-like style to see the size of its subfolders. Scanning is done in a thread, so you can already see results while TreeSize is working. The results can be printed in a report.
Here is complete features (taken from authors site):
What’s New in version 2.3.1:
- Folders without subfolders are now expandable as well and show the files, similar to the [Files] items.
- A few minor improvements have been incorporated.

File Size / OS:
- 1.55 MB / Windows 9x - ME - 2000 - NT - XP - 2003 - Vista
Download TreeSize Free 2.3.1: