Windows is your security foundations, if it is weak, then everything on top of it can collapse. For instance, a malware could exploit a known Windows vulnerability in a service running by default, to execute, but if this vulnerability is patched, and that this service is disabled, then the malware is dead in it's track. Thus, you must take care of Windows itself first, this is as critical as making the foundations of a building. In what follows, we will see together how to decrease your exposure to various threats, by disabling unneeded Windows services, configuring few Windows options, setting up updates, controlling what is starting up, setting strong passwords, and by setting up some critical programs rights and privileges. This guide applies to Windows XP Home Edition and Professional Edition, Windows 2000, and Windows 2003. However, some general advices are true for all OS, so it's still good to read this guide even if you have Windows 98.