Anti-virus software
From HelpDeskWiki
Check that anti-virus software is reputable, updated, and not expired. Be wary of online virus scanners; most do not seem to find as much as the version installed on your computer, they seem to give more false positives, and many do not offer cleaning capability. BitDefender (http://www.bitdefender.com/scan8/ie.html) seems to be the best online scan by far, and it also removes what it finds. (Be sure to read the warning and check the settings!) Kaspersky's (http://www.kaspersky.com/virusscanner) online scan often finds even more malware, but it does not remove anything.
According to the Virus Bulletin test (http://www.virusbtn.com/vb100/about/index.xml), Avast! (http://www.avast.com/eng/avast_4_home.html) is consistently the top-rated (free registration required) antivirus program, and it has a free version. Computer scientists criticize that test because it allows vendors to improve their ratings retroactively through program improvements and because it places too much emphasis on old, no longer circulating viruses instead of the ability to clean computers with current real-life malware. The less industry-based and more scientific tests provided here (http://www.av-comparatives.org/) give a much higher detection rating to other programs. In these tests, the highest detection rate is achieved by AntiVir (http://www.free-av.com), which uses the same technology and virus definition files in its free version. AntiVir did not achieve an excellent overall rating in the most recent of those tests due to some false positives, but these were not critical and most if not all have been corrected in the current version. This graph (http://winnow.oitc.com/AntiVirusPerformance.html) based on testing carried out by the reputable Malware Incident Reporting & Termination (MIRT) team at CastleCops also shows that AntiVir is by far the best antivirus, especially in dealing with new threats. The methodology of the tests is explained here (http://winnow.oitc.com/avcentral.html) and praised here (http://sunbeltblog.blogspot.com/2007/02/recognizing-paul-and-robin-laudanski.html). Do a full scan of your computer, and clean as necessary. Most antivirus and other antimalware programs are currently only fully effective when run in Windows's safe mode and in all user accounts.
Here's (http://www.bleepingcomputer.com/forums/topic3616.html) a list at Bleeping Computer of freeware versions of and freeware replacements for common commercial antivirus and other antimalware programs.
And here's (http://www.bleepingcomputer.com/forums/index.php?showtopic=405) a list including other antivirus and other antimalware programs also containing commercial programs that do not have freeware versions.
Some of the best programs are however not mentioned in one or both of these lists. These include AntiVir (http://www.free-av.com), Comodo AntiVirus (http://www.comodo.com/products/free_products.html), Comodo Anti-Malware (http://www.comodo.com/products/free_products.html), and Trojan Hunter (http://www.misec.net/trojanhunter). See also this thread (http://gladiator-antivirus.com/forum/index.php?s=11163f290db266a3051fba2788a6e43a).
