SpaceSniffer is a good disk space analysis tool. It displays much like SpaceMonger (which I like) but is kept updated without fee. Start as Admin or it will error on C:. It will auto update HD info as the drive is altered so no refresh needed, a nice little program.
Why use it? To get a graphical representation of file/folder space on a hard drive. It is much easier to determine what is eating up you HD with a picture worth a thousand words.Credit: PCMech