I don't like them on either. I like to check the site when I want to, and install when I want to.
First, go into control panel and into the internet security stuff and disable monitoring of your firewall and antivirus etc. (same place as turning off automatic updates I think).
Then, in control panel go into the administrator folder and to the 'computer management' (I think, not on windows here..) icon, and there to the 'services' tab if it isn't there already. find the automatic updates service and/or the windows security service and right-click it and click properties to stop it and disable it. That'll stop it opening up.
Just also make sure you do have a firewall and antivirus running, and periodically goto www.windowsupdate.com and install the updates.