My neighbor just bought a new PC with a 400GB drive! His wife's question to me was "What WILL he do with all that space?" My answer? "All drives are too small if you own them long enough!" Do you find yourself "fiddling" with files from time to time just to conserve space? One week you have multiple gigabytes free and the next thing you know you can't install new software for lack of space. Windows Explorer is a lot of things, but is't not terribly helpful in identiying big space-eating files.
TreeSize, from Jam Software, Inc., scans your drive and builds a nice directory listing indicating sizes. You can then navigate through the resultant tree, and see exactly where those space hogs are. It displays directory and files sizes as actual file size, allocated size, and as percentages. TreeSize is launched from the context menu of a folder or drive and then shows the size of that folder, including its subfolders. You can expand this folder and see the size of every subfolder, etc.
For those "tight-of-wallet" there is a freeware version; but more fully featured commercial ‘Professional’ version is also available. It includes charts, data export, and more.
Thius is a nice little utility that may come in very handy for you some day. It's very specialized and does only what it's designed to do --- but does it very, very well.
Enjoy.
gll