Those who missed out on downloading Microsoft's free anti-virus beta package June 23 don't have to wait for the general release later in 2009. Several security software vendors offer—and have for years—free anti-virus applications, using them as a gateway for users and partners.

Microsoft is receiving mixed reviews of its Microsoft Security Essentials, billed as free basic protection against malware for consumers. Microsoft closed the beta version after more than 700,000 downloaded the software within 24 hours of it becoming available.

While tech reviews say the package appears to perform well enough compared with some fee-based products, many have questioned the wisdom of trusting Microsoft to secure the very platform that is vulnerable to uncountable threats and exploits.

>> Check our list of the best free anti-virus products.

Several analysts and bloggers have added their voices to the chorus, musing about whether "adequate" and "basic" protection is good enough. Among those voices are security software vendors that have offered free version of their products for years. To them, free anti-virus software is a means to an end—getting users acquainted with their products and opening opportunities for partners.

"We want to lower the barrier to entry to enable end users and small and midsized businesses to get to know the products and how to use them," says Juan Santana, CEO of Panda Security, a Spain-based security company.

Panda is among the many tertiary anti-virus vendors that offer free anti-virus products. Among them are AVG, BitDefender, ALWIL Software and Avira. These vendors offer products that are not just free trials, but full implementations of an anti-virus solution. Vendors such as ESET and Kaspersky Lab offer low-cost solutions that provide better functionality but still lack the power of a Symantec Endpoint Protection or McAfee Total Protection suite. The idea is still the same, though: Get users familiarized and offer better performance and functionality with for-fee plans.

For Panda, Santana says a free offering—including an online, cloud-based anti-virus service—is the best way to go for a company that has virtually no share in the U.S. market. Panda is one of the best-known security brands in its home market of Spain, where it holds a 30 percent share. Globally, Panda's market share is less than 3 percent, and in the United States it's less than 1 percent. By offering free software and services, Santana says Panda aims to increase its U.S. market share and create more opportunities for its resellers.

"The free offering is a good way to get the company known, and then offer the premium product," Santana says. "We go to them later with the full array of offerings on the corporate side, including managed services."

Free anti-virus protection is a trend among European security vendors. Panda is from Spain. BitDefender is from Romania. Avira is German-based. AVG is headquartered in the Netherlands, and ALWIL is from the Czech Republic.

Generally speaking, these purveyors of free anti-virus software are in agreement that free applications are only an entry point and do not provide the security protection or the manageability of business-class or enterprise-class solutions.

When About.com's Mary Landesman tested three free anti-virus products—AVG, Avira and ALWIL's Avast—she found the performance and responsiveness adequate for casual users. As she wrote, these products are designed to find known viruses and worms "in the wild," but suffer from poor user interfaces, automated and static online support resources, and a lack of spyware and adware protection.

Like Panda, BitDefender is looking to expand upon the success it has enjoyed in its home market by building out a U.S. channel. While it offers a variety of software and hardware products, its free anti-virus offering is designed purely as an entry-level offering.

"Our products are designed to be easy to use and easy to install for the midsized company, and that translates into saved time and money," says Keith Alston, BitDefender's director of channels in North America.

Microsoft's launch of a free anti-virus product may help these smaller vendors by validating the free-to-paid model. However, many of these vendors say Microsoft Security Essentials may confuse consumers and lower security awareness and practices among the most vulnerable users connected to the Internet.

"It's important to recognize that Microsoft's role in the Internet security realm is much like your relationship with your trusted family doctor. They can help diagnose the problems. In addition, they treat many general ailments. In the end, though, they are not a replacement for a specialist when you need one," AVG CEO J.R. Smith said in a statement.