We recently reviewed four free antivirus programs from AVG, Microsoft, Comodo and Avast. Now we’ll continue with four more frugal possibilities from Returnil, Outpost, Avira, and Panda -- again, all providing at least traditional real-time protection for no charge.

Let’s check them out:

Returnil System Safe Free

Returnil System Safe Free is provided for personal home use. In addition to basic virus, spyware, and other malware protection, it features a virtual mode to further protect your system when using untrusted applications and websites. Though the free registration is optional, it’s required for continued virus and password protection after 30 days.

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 you’re unsure about or are browsing untrusted websites. It’s 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 can’t 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 can’t schedule on-demand scanning with Returnil System Safe Free. You’ll need to remember to do it yourself.

Outpost Security Suite Free

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 what’s 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; you’ll need to remember to do it periodically. Additionally, there’s 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.

Avira AntiVir Personal

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 doesn’t 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.