Currently Being ModeratedFeb 12, 2013 4:50 AM (in response to TechApple)
(You have seperate internet security software on your windows partition.)
In Windows 7 Microsoft Security Essentials requiring download from Microsoft was the best Application to have for Windows OS.
In Windows 8 Microsoft has upgraded Windows Defender which is an Automatically Started Service in the OS. You do not want or need anything else.
Press Command and x key simultaneously and choose Computer Management from the pop up; then select Services within Services and Application to see Windows Defender Service among active Tasks. It is part of the OS and nothing else should be used.