Updated April 2014
Microsoft Security Essentials (version 4.4) is easily one of the best free antivirus program available. I like it because it's produced by Microsoft and because it's really easy to see if the program is protecting you as it should be.
Important: Microsoft Security Essentials provides constant virus protection, also called on-access or resident protection, for free. This means that Microsoft Security Essentials can completely replace antivirus software from companies like McAfee and Norton that charge for their software and for yearly access to updates.
Note: There are inconsistent reports that Microsoft has recommended that people do not use just MSE, but instead use a third-party antivirus tool from another company. For what it's worth, I use MSE on many of my computers and it seems to protect them just fine. Microsoft's latest comments can be found here.
- Provides resident protection from viruses, spyware and other malware
- Virus definitions are updated automatically and regularly
- Very easy to install
- Does not attempt to install unrelated software
- Works with Windows 7, Vista, and XP (It's included with Windows 8)
- Does not include a silent mode (so you might be bothered during gaming)
- Microsoft Security Essentials includes fully functional engines to guard against viruses and most other kinds of malware.
- Includes a very easy to use on-demand scanner for manual malware checks.
- Windows 7, Vista, and XP are all supported operating systems for Microsoft Security Essentials.
- Simple green/red indicator makes it very easy to see if you're protected.
- Microsoft Security Essentials updates regularly to keep its malware knowledge current.
My Thoughts on Microsoft Security Essentials
Security Essentials is Microsoft's first attempt at an antivirus program, free or otherwise. My take: they did an excellent job. It was super easy to install and even easier to understand and use. Microsoft Security Essentials even trumps most of the popular, expensive antivirus options out there.