Hmmm? Comments? Wiki : "Before Windows 8, Windows Defender featured antispyware capabilities. It included a number of real-time security agents that monitored several common areas of Windows for changes which may be caused by spyware. It also included the ability to easily remove installed ActiveX software. Also integrated support for Microsoft SpyNet that allows users to report to Microsoft what they consider to be spyware, and what applications and device drivers they allow to be installed on their system. In Windows 8, functionality has increased to offer antivirus protection as well. Windows Defender in Windows 8 resembles Microsoft Security Essentials and uses the same virus definitions."
So... do ya need Kaspersky or NcAfee or Symantic or whatever?