Are you talking about hte security center pop ups? The one that tells you about hte Anti-Virus and such.
You should be able to go under the Control Panel and there should be the security Center. Load it up and click on Dont show me these reminders ever. It will not prompt you again. Also if you just click on it in the taskbar it should do that as well. Just make sure you click the link that says:
"Change the way Security Center wamrs me" or something like that.