To help protect your computer against malware, make sure you are using up-to-date antivirus and antispyware software. Windows Defender, included in Windows, is anti-malware software that can help protect your computer against spyware and other unwanted software, such as adware. Windows Defender is installed and turned on by default. For more information about Windows Defender, see Using Windows Defender.
Windows doesn't include antivirus software. If you don't have up-to-date antivirus software on your computer, you should immediately install it because if your computer is connected to the Internet without antivirus software, it can have spyware or malware installed on it without your knowledge. You can purchase antivirus software online by going to the Windows 7 security software providers website.