You do not have to burn to a media as it is not neccessary and a waste of time since the devs will update the script often in it's lifetime. If you do decide to burn it, the dev and mods on this site might
not offer any support since this board is mainly for the How-To and ISPConfig.
As to your problem with extracting the file, what type of internet access do you have? I downloaded the 19.9mb script
and extracted just as the How-To explained it and it extracted fine. Maybe you are copy/pasting the wrong link at sourceforge?
Now, go back to the tutorial and find the info that tells you how to uninstall/remove ISPConfig. There are more than a handfull of posts here that tell you also. then try the fallowing under root (each line is an individual command):
tar xvfz ISPConfig-2.0.9.tar.gz