You can click “properties” on a folder and after adding up all the files it will tell you both the total size of files, and the space they take up on the disc. That’s might help you find large folders. And empty your Recycle bin and use the clean-up utility to get rid of stuff you don’t need.
Haha, that’s the problem with search engines: hitting the right terminology. I was using “file allocation” and not getting much. With “disk usage”, however, I popped up this EXTREMELY handy bugger:
Not sure if it’s what your looking for, but I really like SpaceMonger (I think you can get a free trial).
Another is WinDirStat, another is SequioaView… there are a few others out there, but I really only like Spacemonger. That HD Graph looks good, too. Maybe I’ll give that a shot.
Basically, it shows you a graphical representation of all the files on your drive. Bigger files are bigger in size, etc.