In our latest report on staying safe in cyberspace, 7 online blunders, the top mistake we warn about is assuming your security software is protecting you.

Now, a study just released by the National Cyber Security Alliance, underscores our advice by suggesting that many online consumers think their computers are more secure than they really are.

The study, performed by Zogby International and software maker Symantec, polled 3,000 online users and scanned the computers of 400 of them.

Among the findings:

• 75 percent of respondents said they were using spam filters, while only 52 percent actually had a spam filter installed.
• 81 percent of respondents said they were using a firewall, but only 42 percent indeed had a firewall installed on their computer.
• On the other hand, perceptions nearly matched reality for anti-virus and anti-spyware software.

To avoid becoming a victim of online threats, you need to run effective security software. For lots of free advice on how to protect yourself online, and which mistakes to avoid, visit our new Online Security Guide.

—Jeff Fox