Download Simple Directory Analyzer, to understand your folders
Simple Directory Analyzer is a free utility that will help you analyze a directory or even a partition.
You can drag and drop a folder from Windows Explorer to Simple Directory Analyzer, in order to get a file listing for this folder, a list of all file types it contains, a list of duplicate files and another one of hidden files.
You will also be able to sort your files by name, file type, location and size.
The program also enables you to draw graphs from your information (graph of file types or of the biggest files currently).