Best Free Anti-Virus

avast! Home Edition is a full-featured antivirus package designed exclusively for home users and non-commercial use. Both of these conditions should be met! Our company offers the Home Edition free of charge, since, in our opinion, it is possible to avoid global virus spreading by efficient prevention; however, many users are not able to or do not want to pay for antivirus software. This page will show you the most important features of this program.
avast! Free Antivirus is perfect for people who send e-mails and surf popular websites.
* Antivirus and anti-spyware engine
* New avast! Intelligent Scanner
* New Silent/Gaming Mode
* New Behavior Shield
* Real time anti-rootkit protection
* Smart virus updates
* avast! Community IQ
* Behavioral Honeypots
* Green computing
* avast! iTrack
* File System / Mail Shield
* Web Shield
* IM / P2P Shield
* Network Shield

You register free to get an activation code via email, totally free

AVG Free is one of the most popular free solution available at no cost to home users and provides the high level of detection capability that millions of users around the world trust to protect their computers.
* Easy to use, low system resources
* Automatic update functionality
* Real-time protection as files are opened and programs are run
* AVG’s Virus Vault for the safe handling of infected files
It’s always been our philosophy at AVG that everyone has the right to basic computer security at no charge. And our 110 million users think we’re doing a pretty good job. Ideal if you’re planning to spend time online and/or you regularly exchange files with friends.
* Surf, and search with confidence, while LinkScanner® keeps you safe from harmful sites
* Get online and offline protection from viruses, spyware, and other nasties
* Enjoy consistently high-speed PC performance with our new enhanced virus scanner
* Automatic updates keep your protection current
AVG Anti-Virus Free is only available for single computer use for home and non commercial use.

Avira AntiVir Personal - FREE Antivirus is a reliable free antivirus solution, that constantly and rapidly scans your computer for malicious programs (such as viruses, Trojans, backdoor programs, hoaxes, worms, dialers etc.), monitoring every action executed by the user or by the operating system and being able to react promptly when a malicious program is detected.
19 March 2008 – Users of Windows Vista can rely on the award winning protection of Avira AntiVir in the future: The anti-virus software will be fully compatible with Service Pack 1 from Microsoft for the 32-bit and for the 64-bit versions of Vista.

Ad-Aware Internet Security, anti-virus & anti-spyware all in one
Real-time protection against virus, spyware, trojans, rootkits, hijackers, keyloggers, and more!
Core Virus and Spyware Protection Trusted by Millions Worldwide
We have taken the security product millions of people know and trust one step further to give all users the power to protect themselves online. By combining Lavasoft's pioneer anti-spyware technology with traditional anti-virus protection, Ad-Aware Free now features complete malware protection, that won't slow your computer down!
Ad-Aware Free Internet Security features real-time protection, advanced Genocode detection technology, rootkit protection, automatic updates, and much more — to ensure that you have the power to protect yourself online.
* Shop, bank, e-mail, and watch videos online
We keep you safe from password stealers, keyloggers, virus, spyware, rootkits, trojans, online fraudsters, identity thieves and other potential cyber criminals.
* Download photos, music, and other files with confidence
Ad-Aware's behavior-based detection finds suspicious files and threats before they integrate into your PC and attack your personal information.
* Get Peace of Mind
Know that your personal information is kept safe from dangerous intruders and prying eyes.
* New!Core Malware Protection
* Ad-Watch Live! Basic integrated real-time protection
* New!Genotype Detection Technology
* New!Behavior-Based Heuristics Detection
* New!Rootkit Removal System
* New!The Neutralizer Malware Removal Tool
* New!Download Guard for Internet Explorer
* New!E-mail Scanner
* Minimal Strain on System Resources
* Easy to Install & Use
* Automatic Updates
Just set and forget - we'll keep you safe.

PC Tools AntiVirus Free Edition, you are protected against the most nefarious cyber-threats attempting to gain access to your PC and personal information. Going online without protection against the latest fast-spreading virus and worms, such as Netsky, Mytob and MyDoom, can result in infections within minutes.
Once infected, the virus will usually attempt to spread itself to your friends, family and associates by accessing your email contacts and networked PCs. The infection may also allow hackers to access files on your PC, use it to launch attacks against other computers and websites or to send mass SPAM email.
That's why PC Tools AntiVirus Free Edition provides world-leading protection, with rapid database updates, IntelliGuard™ real-time protection and comprehensive system scanning to ensure your system remains safe and virus free. PC Tools products are trusted and used by millions of people everyday to protect their home and business computers against online threats.
* Protects your PC as you are working, surfing and playing
* Detects, quarantines, disinfects and destroys Viruses, Trojans and Worms
* IntelliGuard™ protects your computer against threats in real-time
* Automatically checks for frequent updates against the latest threats
* Best of all it's FREE. No catches, limitations or time-limits.

This is an easy install & forget program that sets itself up for you

Comodo is developed by one of the world’s leading IT security providers, Comodo AntiVirus leverages multiple technologies (including on demand & on access scanning, email scanning, process monitoring, worm blocking and host intrusion prevention) to immediately start cleaning or quarantining suspicious files from your hard drives, shared disks, emails, downloads and system memory.
* Detects and eliminates viruses from desktops and networks
* Constantly protects with real-time On Access scanning
* Proactive Heuristic analysis intercepts unknown threats
* Host Intrusion Detection blocks malware before it can run
* Daily, automatic updates of virus definitions
* Simple to use: install and forget

You can choose to install the Anti-Virus on its own or with the Firewall