Installing Microsoft Security Essentials

Here's how you can install Microsoft Security Essentials (MSE) and enjoy the benefits of Microsoft's free (and good) antivirus solution. Keep in mind that MSE will only install and auto-update on machines with a genuine copy of Windows. The following instructions are specific to Windows Vista, but should work similarly in Windows 7, with some small differences for Windows XP.

1. Determine whether you have a 32-bit or 64-bit version of Windows installed.
1. Click on the Start button.
2. Right-click on "Computer".
3. Click on "Properties".
4. In the resulting window, under the "System" heading, look for "System type".
1. This will be either "64-bit Operating System" or "32-bit Operating System".
2. This will tell you whether you have 32- or 64-bit Windows installed.
5. Alternatively, open a command prompt window.
1. While holding down the Window key on your keyboard (the key with the wavy window), press the "R" key.
2. Type "cmd" (without the quotes) and hit "Enter".
3. Type "echo %processor_architecture%" (without the quotes) and hit "Enter".
4. If "X86" is printed out, you have 32-bit Windows installed; if "AMD64" prints out, you have 64-bit windows installed.
   
6. Most people will have 32-bit Windows installed.
2. Download MSE from http://www.microsoft.com/security_essentials/
   
1. Remember the download location: you will need to run this file later.
2. Usual download locations are either C:\Users\<your-username>\Downloads (if you don't want to share the file with other users on your computer) or C:\Users\Public\Downloads
3. Download the latest virus definition files (large: ~47MB): http://go.microsoft.com/fwlink/?LinkID=87342 (if you have 32-bit Windows) or http://go.microsoft.com/fwlink/?LinkID=87341 (if you have 64-bit Windows).
1. Remember this download location too: you'll need it later.
2. Disconnect from the Internet.
4. Uninstall your existing antivirus
1. Generally speaking, any installed antivirus program will keep any other antivirus program from being installed.
2. Open "Programs and Features" (Start >> type "programs" in the search box >> click on "Programs and Features" from the resulting list).
3. Right-click on the antivirus program you want to uninstall and choose "Uninstall".
5. Install MSE by clicking on the installation file downloaded earlier.
6. Once the above step is complete, run the downloaded virus definition file.
7. Open MSE (look for a little house-like icon with a flag on top of it in the system tray and double-click it).
8. On the right hand side, under "Scan options:", choose "Full"
9. Click on "Scan now"
1. MSE's virus scan will take a while to complete (depending on how much data you have stored).

You're done! From now on MSE should be able to auto-update its virus definition files either through Windows Update or by itself. You can re-connect to the Internet once MSE and subsequent virus definition installations are over.

If you notice any errors or discrepancies above or you want to suggest any corrections, please leave a comment.