OS: Windows Vista Home Premium
Standard user can turn off Security Center Alert without requiring a administrator password credentials. Standard user account should be restricted on changing Security Center Alert and only the Administrator can change Security Center Alert. This should be change in SP1. Why would you allow a standard user to turn off the security center alert in the first place? for convinient, administrator create standard account to restrict user from changing the setting and letting a standard user change this setting is a mistake.

GT
A Standard User can change the way they are alerted, but making changes to each specific application that the Security Center monitors still requires admin approval. An admin can simply set all of these applications to their default settings and this would make the way the user is alerted redundant, since the alert would never appear.

Ronnie Vernon Microsoft MVP Windows Shell/User
"GT"