For .tgz on linux use:
tar -zxvf "name_of_tgz"
You could also use Ark/KArchiver on KDE.
In Windows you can relabel the archive to *.tar.gz. Winzip will then deal with it. Essentially, the archive is a gzipped tar file.
It seems Mozilla (Windows AND LINUX) is unable to correctly download that file. v 1.2.1 through 1.4 beta are all broken. Tried on 3 machines, multiple times. IE works fine. Thanks for your posts.