Finding out what folders and files take the most space on a Windows computer?

1) What good software out there already exists that allows one (preferably visually) see what folders and files are taking the most space on one's computer (Windows Vista compatible)

2) Say I wanted to write开发者_如何学Python a this program myself, what opensource tools out there can I use to get started?

Thanks!

1) You can try WinDirStat: http://windirstat.info/

2) I don't think you need open source tools, you could write it in Java or .NET just by using what is already provided with the languages.

Yes there are plenty of them. For example check out these..

I use Sequoia View http://www.snapfiles.com/get/sequoia.html. As to the second part of your question I don't know sorry.