Does anyone have a link to a free tool that will quickly show me which folders on my hard disks are taking up the most disk space?

For instance, let's say I'm down to a few hundred megs on drive c: and I want do do some cleanup. I don't mind deinstalling programs, but I'd love to be able to see a graph of which folders on drive C are taking up the most space, and would therefore get me the most bang for my buck in terms of which programs to deinstall.

An example of the sort of thing I'm looking for is here (look at the second screen shot), but that link is for an Access 2000 application. I'm looking for a straight windows-app that doesn't piggyback off of Access.

Anyone got a good one they know about or use?