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This is a beta release.
You can visit the Microsoft Connect page to register for the beta program. Please note that this is a limited beta available only to genuine Windows users.
New features in the beta of Microsoft Security Essentials include:
Windows Firewall integration – During setup, Microsoft Security Essentials will now ask if you would like to turn the Windows Firewall on or off.
Enhanced protection for web-based threats – Microsoft Security Essentials now integrates with Internet Explorer to provide protection against web-based threats.
New protection engine – The updated anti-malware engine offers enhanced detection and cleanup capabilities with better performance.
Network inspection system – Protection against network-based exploits is now built in to Microsoft Security Essentials.