All you have to do is start CFS3, hop in the first available aircraft (usually the P47), fly it for a few seconds, exit the game, and start installing OFF. It doesn't look to me like that is the problem here. Have you got your regional settings set to English (UK, USA, South Africa). I'm not sure exactly how to do that as I've never had to, but Catfish, Olham, or Axenti might be able to help you, since they are from your neck of the woods.
CJ