Two years on, and apparently Blaster Worm still prevalent in the wild.

The article looks at some of the reasons, but many of them relate to people re-installing the OS and then not updating and the large numbers of individuals not updating their systems from Windows XP SP1 to SP2.

How do you get people to update to the latest version and protect their machines?

In a large company where they have policies and use the functionality of Group Policy and Software Update Services to force individual clients to be kept up date. Ironically, these organizations are usually the ones with firewalls and email filtering that probably means these types of attacks do not make it through in the first place.