I've downloaded iATKOS_v7 to install on the Acer 4730z

What I need to know is,
The file I Downloaded is .rar Do I just burn that file to DVD?
If I try and us Stuffitexpander.app it gives an error, Here's what it says,

"The file "/Users/musick7/Downloads/iATKOS_v7.rar" does not appear to be compressed or encoded. It is advised that you obtain further information about the contents of this file from the sender or provider of the file."

its a total of 3.87GB Am I doing something wrong?
I can't seem to find a Tutorial for this Acer Laptopů But every forum I've read with Acer Aspire 4730z in thread says to use iATKOS_v7 but no one has a Tutorial out there floating around... Can anyone assist me or point me in the right direction?