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    • Microsoft Security Essentials Prerelease

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        • IMPORTANT NOTE: If your computer is already running a version of Microsoft Security Essentials, you will have to uninstall that version first, then install the prerelease version available for download on this page.

          Installation steps:
          • Read the KB article to determine whether your computer is running a 32-bit version or 64-bit of the Windows operating system.
          • Uninstall any existing version of Microsoft Security Essentials from your PC (using "Add or remove programs").
          • Click the Download button on this page to start the download for the appropriate version (32-bit or 64-bit) and click 'Run'

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