Beginning from version 1.2, Spybot-S&D allows you to immunize your computer against some spyware. It currently offers three different immunities:

Permanent Internet Explorer immunity

The permanent immunity works on some Internet Explorer control options that are partly visible in the Internet Explorer interface, partly hidden in the registry only. It adds domains known to contain bad contents into the Restricted Zone, thus blocking installation of executable code from those pages; it also adds block options for bad executable code by its ID, and it sets known tracking cookies not to be accepted by Internet Explorer.

Permanently running bad download blocker for Internet Explorer

This is a second layer of protection for IE. While the Permanent Immunity blocks installers by their ActiveX ID, this one blocks anything that should come through by different aspects.
You can view a log of blocked installers in the Tools / Resident section.

Permanent Opera immunity

This list shows all Opera profiles, and how many of the plugins that Spybot-S&D knows as bad are already blocked in each profile. To set the complete protection, just tick the checkbox in front of the profile you want to protect. To remove the protection, untick the checkbox.

Not many browser plugins are currently working for Opera, but the attempt to install some may crash Opera, and ActiveX support for Opera is available in third-party beta software, so use this function as a precaution against future misuse of Opera through spyware.