Free and open essential software for Windows

I have a nice list of free and open software for Windows as replacement
of proprietary software. A nice to have list for the ones who wants a
smooth path from Windows for Linux and someone who needs to run the same
software in Windows as in their Linux PCs.

http://www.thesimpledollar.com/2006/12/01/30-essential-pieces-of-free-and-open-software-for-windows/