Be designing a computer network properly you can help ensure that it minimizes the effects of malware outbreaks such as worms and other assorted malcode. One of the simplest network design concepts is to use a router to screen traffic going to and coming out of subnets. This is also known as a "screened subnet" and is not a new idea but one that is simply, in my experience, not used widely. What would be an example of screened traffic you ask? Well for one you might want to screen out the NetBIOS traffic between subnets. Doing this would cut down on any worms trying to spread via network shares. Food for thought isn’t it? You may wish to give this article a read if this subject is of interest to you.