A two-week study has been conducted by Webroot, a company that develops anti-spyware products, on Windows Defender which is Microsoft’s anti-spyware program on Vista.

Twenty-five malicious code samples has been tested and 84% of them was not detected by Windows Defender. The codes that were not detected consists of keyloggers, spyware, and Trojan horse programs. Most of them are not compatible with Vista but the others were able to install on the PCs with Vista operating systems.