Just right click on the game in the list and there should be a choice not to auto update.
I have done so on my copy of WH2. And other games, since auto update can take a huge hit on my bandwidth.
BUT EVERY TIME I START UP THE GAME IT STARTS UPDATING
Primary updates are necessary for the game to run, after it, you can run STEAM on offline mode and then run the game, so it does not update automatically.
Yeah but in some games like Dawn of War 2 you need to be online to play the game with internt connection to connect to your mirosoft account!