Free antivirus software protects against viruses, worms, trojans, and spyware. Free antivirus software is available for Windows 7, Vista, and Windows XP. Following is a list of the most popular free antivirus software for Windows.
Panda takes free antivirus to a whole new level with Panda Cloud Antivirus. The only free cloud-based scanner, Panda antivirus software takes all the processing off your PC, giving you a lighter, faster, and more proactive antivirus protection.
2. AVG Free
AVG Free Edition provides free antivirus protection for Windows XP/2000/NT/ME/98. Installing only 30Mb of files and 4 running processes, AVG Free Edition is the smallest antivirus scanner we've tested and may well be the best choice for an older PC with severely limited system resources.
AVAST 4 Home Edition provides free antivirus protection for Windows XP/2000/NT/ME/98. The scanner installed just under 40MB and 6 running processes to our Windows XP Pentium 4 test system, taking a slightly bigger toll than other free antivirus scanners, but still well suited for older PCs or those with limited system resources.
AntiVir PersonalEdition Classic provides free antivirus protection for Windows XP/2000/NT/ME/98. The svelte scanner installed only 34MB and 3 running processes to our Windows XP Pentium 4 test system, making it an excellent option for those with older PCs or limited system resources.
5. PC Tools
PC Tools AntiVirus guards against Windows only malware, including viruses, worms, trojans, spyware and adware. With a simple, straightforward interface, PC Tools AntiVirus is as easy on the eyes as it is easy on the system resources.
For Windows XP SP2 and above, BitDefender Free Edition is an on-demand scanner only. This makes it unsuitable as standalone antivirus protection but it would make a great addition as a second opinion scanner to already installed protection. In addition to full system scanning and quarantine, BitDefender Free Edition features right click and scheduled scanning.