Avast Free Antivirus 5 is well designed and generally easy to use. In most respects, it's a somewhat scaled-down version of the paid Avast Pro Antivirus 5. The installation process was quick and painless, and I had to click through only a couple of screens before it started installing. The main screen is laid out nicely and is easy to use, though not without its flaws. A slightly annoying aspect of Avast Free Antivirus the fact that a banner advertising its paid counterpart will appear on the Summary tab, but since it's unobtrusive, it isn't a serious issue.

First, the negatives: In traditional malware scanner tests (which rely predominantly on signature files to identify malware), Avast Free Antivirus detected 94.8 percent of samples, which is neither particularly good nor bad (top scorers detected over 99 percent of malware samples). It also did a decent, though not outstanding, job at detecting malware in our real-world malware detection tests: It completely blocked 76 percent of attacks (which is right about average), and partially blocked 4 percent of attacks. The top performer in this test, the free Comodo Internet Security Premium, completely blocked 96 percent of attacks.

But on the plus side, Avast Free Antivirus didn't falsely identify a single "safe" file as a piece of malware, the only free product we looked at that did so. Avast Free also did a good job at disinfecting a PC, detecting all infections on our test PC and removing all active components of malware infections 80 percent of the time, which set the pace among the free products we reviewed.

Scan speeds are very good, too. It scanned 4.5GB of data in 90 seconds in the on-demand scan test (that is, scans started by pressing the Scan Now button). This was a close second to Avira AntiVir Personal, which completed the test in 87 seconds. And Avast Free completed the on-access scan speed test in 3 minutes, 40 seconds--tops among the products we looked at. This is a good test to tell how well security software can scan for malware when files are opened or saved to disk.

Avast Free Antivirus also had a low impact on PC performance. Our test PC with Avast Free installed booted up in 44.5 seconds, which is roughly 4.5 seconds slower than the PC without antivirus software installed, but less of a slowdown than the average of the free antivirus software we looked at. The same held true for many of the other speed tests we performed.

Avast's support options outclass other free antivirus programs. Unlike most free antivirus software which only comes with online support, Avast offers free telephone support, so you'll actually be able to talk with someone directly if you have a problem. For some, that alone may be worth the tradeoff of good-but-not-top-notch malware detection. Although it wasn't the top performer in every category, Avast Free Antivirus is an excellent, well-rounded free antivirus program.