1) Go to your Start Menu > Control Panel
2) Switch to Classic View if you have not already
3) Double click on the "Windows Update" icon
4) Look to the left and click on "Change Settings" as shown below:
5) You should see that you are currently set to automatically update. You should disable this, and select the option shown below. This will check for the updates, but not download or install anything until you give the go-ahead.
Hope this helps, if you have any further questions let me know!