Apple OS X Mountain Lion brings pile of new features like dictation and automatic update downloads. While we are fan of automatic app and system updates, some like to have control over the bandwidth being used. Follow these steps on how to stop it.
1. Open system preferences and choose software update.
2. Click on the lock icon to unlock preferences.
3. Make sure to uncheck "Download newly available updates in the background".
4. Optional but not recommended: uncheck “Install system data files and security updates”.