How are you trying to unpack it? Under Ubuntu, I usually just right-click and choose “extract here”. I know you say it’s a good file, but have you tried downloading it again, because a corrupt file seems to be the chief cause of such messages.
[FONT=Verdana]Firstly, I seldom use the command line, so mine might not be the best advice, but I think you’re missing the “z” to gzip your tar, which would explain the error message stating that it’s not in gzip format when you come to unpack it.
You might find some help here. (I know that’s the Ubuntu forum, but I’m sure tar is tar, whichever distro you’re using.)[/FONT]