Yesterday I was trying to do some file clean-up in my hard drive and I realized how uncomfortable it is to check directory size in Windows! You have to click on each folder one by one and either wait to the alt text to appear or open the Properties window.
This is why I'm glad I found this utility today. Directory Size Calculator takes whatever folder you select and quickly calculates its size recursively, which means it also analyzes and displays the size of subdirectories, both in GB or MB and in percentages.
The program has a very simple design and it's deadly simple to use. On the downside, I missed an option to save the listing in some way or even print it out.