Using TreeSize Free edition, you can immediately see which folders and sub-folders are taking up the most hard disk space. Once you have that info, it’s a piece of cake to quickly free up hard drive space taken up by temp files or other useless data. TreeSize doesn’t even require any installation, you can just double-click on the EXE file to run it. This is actually really great because it means you can copy the entire program to a USB stick and run it directly from there on any computer. Just make sure to pick the Zipped Executable when downloading (http://www.jam-software.com/treesize/).
Once installed, click on the Scan menu item and choose a drive that you would like to analyze.
Now you can see and browse the list sorted from largest size to smallest size all of the folders on your hard drive.
Using the Windows Explorer type interface, you can click on the plus signs next to each folder to view all of the sub-folders and their sizes.