-> While the above statement (that you arent likely to be attacked) may be true, it is also a fact that while whats on your machine may not be particularly important to someone in the scheme of things, your machine may be used in an attack on some other victim. If , for instance, you are an IRC user, and your security (especially in a Microsoft environment) isnt high enough, an attacker may first gain control of an IRC router, then use that router to search for an endless array of easily-acquired zombie agents (like maybe yours) to launch his attack on another person or company. So while your individual computer might not be important, think of the bigger picture. It sure wouldn't be nice to have someone DDoS some corporation or govt site only to make it look like it was you.