Downloads from empublic are in .tar.gz format. This is a compressed tar file. Tar is the "tape archive" format, which is simply a way of concatenating multiple files and directories together into one file. The compression scheme used here is gzip.
A gzipped "tarball" can be extracted quite easily on most platforms.
Obtain a copy of winzip from www.winzip.com if you do not already have one, and use that.
Uncompress the file first using
Then have a look at the names of the files included in the tarball by
tar tvf filename.tar (make sure it won't overwrite
anything critical!). Finally, extract the files by using
If you are feeling confident and have the GNU tar (which may be
gtar on systems or just the plain
tar on some others), the file can be uncompressed and
untarred with one command: use
tar xvzf filename.tgz.
StuffIt should be able to handle this format.