You get a lot for your money with F-Secure Internet Security 2010, thanks to its low price ($50 for three users as of 3/10/2010) and extensive features. However, this year's version ranks 11th in our roundup, mainly because of its uneven performance in detecting and removing malware.

F-Secure's cool-blue-and-white interface is easy to use and navigate. The main screen is straightforward; it has three main icons for status, tasks, and statistics. Smaller icons take you to the manual scan feature, the update checker, and the settings screen, while a large green checkmark indicates when things are protected. The button to initiate a scan is too hard to find, though, and the smaller icons on the main screen tend to get lost.

The suite was a strong performer in our system disinfection tests. It detected all active malware infections on our test PC, and disabled 93 percent of the samples. It was also able to completely remove all traces of 53 percent of the samples--more than most suites managed.

F-Secure was perfect at detecting and cleaning up inactive rootkits; it detected 93 percent of active rookits, and removed 87 percent. By comparison, McAfee and Kaspersky, the top performers in this test, each scored 100 percent for detection and removal of inactive and active rootkits.

On tests measuring old-fashioned signature-based detection of malware, F-Secure did very well, finding 98 percent of our samples. (Our top performer, though, had a 99.9 percent detection rate in this test.) Signature-based detection is less important than it was in the past because new threats show up at such a rapid pace that it's nearly impossible for malware signatures to keep up.

However, F-Secure put up a lackluster showing when detecting malware using behavioral analysis (detecting new malware based solely on how it acts), detecting only 40 percent of samples and removing 27 percent. By comparison, the top performers were able to detect and disable over 90 percent of samples. Behavioral detection is an important metric for determining how well a program can detect new malware for which no signature file yet exists, and these results suggest that F-Secure's suite may not be able to respond quickly and effectively to new malware outbreaks.

Overall, F-Secure's impact our test PC's performance was slight. Our test PC took 46.3 seconds to start up with F-Secure installed (just slightly faster than the average for all the suites), and it had little impact on day-to-day desktop tasks. Scan speeds were on the slow side, however; it took almost 6 minutes to scan 4.5GB of data in our on-access scan tests that show how quickly a product can scan files when they're opened or saved. Our top performer, by comparison, was able to complete the test in 2 minutes, 51 seconds.

F-Secure is a solid-enough Internet security suite, and it won't slow your system; but little about this suite stands out, and its disappointing performance in behavioral detection of malware brings its score down.