As of 2015 PC users download the Microsoft Windows Malicious Software Removal Tool from Microsoft's website to scan for viruses. The site also offers a free security program called Microsoft Security Essentials. For scanning without having to install much software, About.com recommends Bullguard and VirusTotal.
The Malicious Software Removal Tool searches and removes common malware and trojans, such as Blaster, Sasser, and Mydoom, claims Microsoft. Updates are available about once a month on the Microsoft website. Use Microsoft Security Essentials as persistent virus protection software.
Check for virus definition updates before starting a Microsoft Security Essentials scan, states About.com. Use a full system scan rather than a quick scan whenever possible to ensure that the programs checks the entire system. Include the master boot record, boot sector, applications running in memory, hard drive and any other attached storage devices.
VirusTotal is a website that allows users to upload files or input Web addresses to scan for viruses, reports About.com. The maximum upload size for any file is 128 megabytes. Its Web browser virus scanner works for Chrome, Firefox and Internet Explorer. Bullguard scans the user's computer for viruses instead of scanning a browser or uploaded file. However, the virus scan requires the user to download the Bullguard browser extension.