The sixth-place finisher in our 2010 roundup of security suites, Avast 5.0 Internet Security ($60 for three users), offers all the basic PC protection features and does a reasonable job at traditional malware detection. It is also fast. However, it fell short at detecting new threats, and it lacks some features present in other suites.

The Avast interface is well-designed, with a clean, sophisticated look that is not only attractive but easy to use. But at times, the product is not intuitive enough: When scanning your hard drive, for example, you'll have to tell the suite what to do every time it finds an infection, and you can't proceed with the scan until you tend to the alert message. While this gives the user control, it can get annoying on a truly infected drive.

Avast did a reasonably good job at stopping active infections on our test PC. It detected all infected files and Registry entries and disabled 93 percent of the infections. However, it removed all traces of malware in only a third of the cases.

Similarly, at detecting and disabling rootkits (stealth malware used to hide other infections), it did well, though it wasn't perfect. It detected and disabled all rootkit samples, but completely removed only 60 percent of the samples--the worst performance in that test. By comparison, our top two finishers completely removed all the rootkits on our test PC.

The Avast firewall works similarly to the Windows firewall: It asks you to designate each network as Home, Work, or Public. The settings offer different degrees of protection: The Public setting blocks the most traffic (since public networks are less secure), while the Home setting allows more traffic through. Work is the default, and it provides a middle ground.

The antispam function is more developed than the firewall. It labels suspected junk with "***SPAM***" in the subject lines (you may still need to set up a filter to move it to your spam folder). It integrates with Microsoft Outlook and some e-mail clients. It can also scan Web-based e-mail clients such as Gmail.

Not all suites offer behavioral detection; Avast does, but it scored very poorly in detecting brand-new malware for which no signature file yet exists. It detected, disabled, and removed only around 27 percent of such samples. By comparison, our top performers detected all, or almost all, samples in this test.

In old-school signature-based detection of a collection of several hundred thousand malware samples, Avast demonstrated a respectable detection rate of 96.5 percent. The top performer in this test detected over 99.9 percent of samples. But given the amount of new malware daily, behaviorial and active scanning tests are more important today.

Avast Internet Security's drag on system performance was hardly noticeable in our tests: It was the top performer overall in our suite of system speed tests, and was near the top in scanning speed. During scanning, Avast, like Norton Internet Security, uses an intelligent scanner to white-list known good files, and thus reduce the amount of time it requires to scan your drive.

The performance of Avast's new suite was a modest surprise, with fast scans and respectable scores, but its problems with detecting brand-new malware makes it difficult to recommend just yet. We look forward to seeing what next year's edition brings.