A reader writes:
Can I use Microsoft Security Essentials with Windows 8?
No—but you don’t need to. Windows 8 includes Windows Defender, a program that provides enhanced protection against viruses and spyware.
If your computer is running Windows 7, Windows Vista, or Windows XP, we recommend downloading Microsoft Security Essentials or another antivirus program. Microsoft Security Essentials is a free* product that helps protect your computer against viruses, spyware, and other malicious software.
For more information on using antivirus software with Windows, see How to get rid of a computer virus.
* Internet access fees may apply while you are downloading the software. To install Microsoft Security Essentials, you must be running genuine Windows on your computer.