When you upgraded your operating system, the installer wizard asked you about the state that you want the automatic updates to be set to. If you choose ON, your OS will automatically search and download all the available updates. If this is the case, you shouldn't worry about downloading updates.
To activate the Automatic Updates on Windows 7, you need to go to Start > Control Panel > Windows Updates > Change settings (from the right side of the screen) > from the drop down menu select Install updates automatically. To perform a search, you can press the Check for Updates button from the same location. It's advised to keep this option ON at all times.