Ollie
Droid Does
If your downloaded firmware ends in a .zip file be sure to extract it once with the aforementioned program (winzip or 7zip). It must end up with the file extension .tar.md5.
Again, make sure that Kies is not running in the background. Odin and Kies do not play nice together.
Again, make sure that Kies is not running in the background. Odin and Kies do not play nice together.