Choice and control
Update Services are turned on if you choose one of the following settings: (a) install updates automatically; (b) download updates but let me choose whether to install them; or (c) check for updates but let me choose whether to download and install them. The Windows Update service is turned on and set to "Install updates automatically" when you choose the express settings during Windows setup.
If you turn on the Update Services, regardless of which setting you have chosen, required updates to some components of the service will be downloaded and installed automatically without further notice to you. If you would prefer not to receive required updates, turn off the Update Services.
You can also choose whether to check for or automatically install Important and Recommended updates for your computer or Important updates only. Optional updates are never installed automatically.
Grrr...
Also trendmicro optimizer turns on updates