Lets check them out:
The Virtual Mode allows you to put your computer into a state where any changes made to files and system are completely reserved when disabling it and restarting the computer. This is great if you want to run a program youre unsure about or are browsing untrusted websites. Its basically an enhanced (but manual) version of traditional sandboxing found in other antivirus programs. You can optionally setup a virtual disk to save files and documents while in the Virtual Mode.
The password protection lets you set a password to lock down the settings for Returnil System Safe Free, so others cant change settings or deactivate it.
Though real-time protection should catch any infections, you should still run a full system scan at least weekly. However, you cant schedule on-demand scanning with Returnil System Safe Free. Youll need to remember to do it yourself.
Outpost Security Suite Free by Agnitum is available for personal use. In addition to protecting against viruses, spyware, and other malware, it offers firewall and spam/junk email protection. Though free, it requires yearly registration of your name and email.
In addition to the basic protection, it has a feature called Anti-Leak that monitors and detects malicious activity of applications and processes. Similar to features of other programs, it provides enhanced protection from Trojans, spyware and other dangers over whats provided by the basic real-time protection.
The Anti-Spam feature is provided for select email client programs: Microsoft Outlook 2000 thru 2007 and Express 5 & 6, Vista Mail, and The Bat. You configure the settings via a toolbar added to the client. The spam protection is based on the bayesian filtering that you can automatically and manually train. You can add addresses to white and black lists. In addition to the real-time protection, you can scan existing folders, great if your inbox is already full of spam.
Keep in mind, you cannot schedule automatic on-demand malware scanning with Outpost Security Suite Free; youll need to remember to do it periodically. Additionally, theres no sandboxing for extra protection in case something slips by and no password protection to lock-down the program configuration, though both are in the paid edition.
By default, Avira Personal is set to detect and protect you from the most common threats. However, there are a few more threats types it supports but doesnt enable protection for, such as malicious applications, fraudulent software, games, and joke programs. You can also manually scan for infections in the boot records.
Though an entry for a complete system scan is automatically created in the Scheduler (at noon every day), you must go in and enable it: click Administration > Scheduler on the left main menu and check the Enabled checkbox.
Like Outpost Security Suite Free, Avira AntiVir Personal lacks sandboxing for untrusted programs and password protection for the configuration.
Panda Cloud Antivirus Free Edition is offered for use in homes and non-profit organizations. It protects you from viruses, spyware, and other malware. Being cloud-based, the heavy lifting is done by their machines. This helps reduce the amount of system resources needed by the application, while still giving you real-time protection similar to other vendors.
A Web browser toolbar is provided, giving you shortcuts to various tasks, such as searching (via Yahoo only), clearing the temporary files, and checking your local weather. Theres also a shortcut to setup ID Protect, which helps you protect and manage your online passwords. Theres also a shortcut to another on-demand malware scanner thats Web-based, called ActiveScan.
It features automatic URL and Web filtering, stopping you from visiting known dangerous sites before you have any chance of becoming infected. Though you must install the browser toolbar to activate this filtering, you can remove it after the installation if you prefer not to have the toolbar (and still keep the filtering).
Behavioral blocking is also provided to help limit any infected applications from doing damage. This is similar to the functionality of Anti-Leak provided with Outpost Security Suite, but doesnt support advanced behavioral analysis on all processes in the free edition.
Panda Cloud Antivirus Free Edition lacks a sandboxing feature and password protection, like some of the others weve discussed. Plus it cant schedule full system scans, so youd have to periodically do it yourself.
I cant really pick any winner among these four free antivirus programs. Each brings interesting features but also lacking others, as well, but ...
If youre concerned about children or other untrusted users messing up the settings or regularly work with untrusted files or sites, you may want to choose Returnil System Safe Free for its password protection and virtual mode.
If your email client or server doesnt provide adequate spam filtering, you may want to go with Outpost Security Suite Free.
If risky browsing may be a problem or youre concerned by system resources, consider Panda Cloud Antivirus Free Edition for its web filtering.
Eric Geier is the founder of NoWiresSecurity, which helps businesses easily protect their Wi-Fi networks with the Enterprise mode of WPA/WPA2 security. He is also a freelance tech writer. Become a Twitter follower or use the RSS feed to keep up with his writings.