Microsoft Security Essentials [32-bit & 64-bit]

Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.

Microsoft Security Essentials is a free download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It's easy to tell if your PC is secure - when you're green, you're good. It's that simple.

Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your Windows-based PC the way you want - without interruptions or long computer wait times.

Download Microsoft Security Essentials

Microsoft Security Essentials x86_x64 EN-US

Microsoft Security Essentials Download Centre

Download the latest definition updates:
Note: You must have Microsoft Security Essentials installed to use the latest Microsoft Security Essentials virus and spyware definitions.

Before you install the correct version of the Microsoft Security Essentials virus and spyware definition updates, you must know:

• Whether Windows XP, Windows Vista, or Windows 7 is running in a 32-bit or a 64-bit operating environment.
• Whether you are logged on to Windows as an administrator.

If you are not sure of your Windows XP, Windows Vista, or Windows 7 environment type, or if you need help verifying that you are an administrator on the computer, go to the Verify your environment and determine whether you are logged on with an administrator account Microsoft website.

After you verify the operating environment, follow these steps:

1. Download the Microsoft Security Essentials virus and spyware definition update file that is appropriate for your version of Windows:
   • 
        Download the file for a 32-bit version of Windows
   • 
        Download the file for a 64-bit version of Windows
   
   Note You must be running a 64-bit version of Windows to run a 64-bit version of Microsoft Security Essentials. The 64-bit versions of Windows include x64-based versions of Windows.
2. Click Run to install the definition update file immediately. Or, click Save to save the file to the computer. If you click Save, remember the folder where you saved the file.
3. To install the saved file, follow these steps:
   • Windows XP 
     Double-click the file, and then click OK.
   • Windows Vista or Windows 7 
     Right-click the file, and then click Run As Administrator. If you are prompted for an administrator password or for confirmation, type the password, or click Continue.
4. When the definition update file runs, a file extraction dialog box appears. The dialog box indicates that the definition update is installing. After the file extraction dialog box closes, you can verify that the virus and spyware definitions were updated. To do this, open Microsoft Security Essentials, click Update, and then examine the virus and spyware definitions status.

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