Small businesses can use Microsoft Security Essentials on up to 10 PCs for free. Companies that don’t want to use some of their antivirus solution licenses for the PCs in their small test labs can also use this free software. Manually installing Microsoft Security Essentials on each PC is a viable option in a small environment, but if you’ve already set up a domain, you can install it with minimal effort.

Here’s how you can install Microsoft Security Essentials without leaving your desk. First, you need to do a little preparation:

  1. Download the appropriate copy of Microsoft Security Essentials.
  2. Right-click the executable and extract the files. If you don’t have file compression software, you can use the free 7-Zip utility.
  3. Copy the extracted files to your server's shared folder.
  4. Download the free PsTools suite and extract the files to a folder on your machine.

With the preparation done, you can install Microsoft Security Essentials. Let's say that you intend to install it on a Windows XP machine named PC1 and the executable is on Server1 under a shared folder named Software. The only thing you need to do is open a command prompt on your computer and execute the following command from the PsTools directory:

Psexec.exe \\PC1 -S

  \\Server1\Software\

  mssefullinstall-XP-x86\setup.exe

   /S /runwgacheck /o

(Although this command wraps here, you'd enter it all on one line.) The /S parameter forces the installer to perform a silent install. (No screens will pop up.) The /runwgacheck parameter forces the installer to perform a Windows Genuine Advantage check. The /o switch tells the installer not to perform a full scan of the PC at the end of the installation. If you want it to perform the full scan, you can omit the /o switch. Note that I obtained the information about Microsoft Security Essentials’ parameters from AppDeploy.

After a few minutes, Microsoft Security Essentials will be installed on the remote PC. Most of the time, you have nothing else to do because the software performs automatic updates. However, in a few cases, I found that a restart was required for the updates to begin.

After you finish installing Microsoft Security Essentials on the rest of your computers, you’ll have a legal, free, and effective antivirus solution up and running in your domain. Keep in mind that this procedure isn’t supported by Microsoft and might change in future Microsoft Security Essentials editions. Also keep in mind that you won’t have a dashboard with which to centrally monitor and configure Microsoft Security Essentials.