Eset NOD32 Antivirus ($72 for 1 year, 3 PCs as of 12/22/2010) finishes ninth in our roundup of 2011 antivirus software. It does a reasonable job at blocking brand new attacks and it's fast, but it has trouble detecting known malware and cleaning up infections, which makes it tough to recommend.

NOD32's main interface isn't too badly designed, but it's limited in what it displays--even in "advanced mode." Where things get messy, though, is in the settings interface. Here, you'll have access to a limited set of features to adjust--unless you turn on Advanced Mode. In Advanced Mode, the settings box turns into a dizzying array of checkboxes and drop-downs, all in a less-than-optimally-designed window.

Things weren't much better when it came to detection: NOD32 detected 89.2 percent of known malware samples, which is the lowest, by far, of the products we looked at. By comparison, the average for antivirus software that we looked at was 96.2 percent, and top performers achieved over-99-percent detection ratings. Eset also lagged behind in cleaning up infections: It was able to detect all infections on our test PC, but it was able to remove all active components only 60 percent of the time, and it removed all traces of malware only 10 percent of the time. Both scores were the lowest in this test, and well behind the pack.

That said, Eset did an acceptable job at blocking brand new malware--it fully blocked 84 percent of brand new malware attacks in our "real world" testing--a decent showing, but not outstanding. Eset also had up a low false-positive rate--it flagged only one good file as suspicious.

Eset shined in system speed tests. When we triggered a scan, Eset was the fastest among the products we tested--it tore through 4.5GB of files in a mere 90 seconds. Its on-access scanner--which kicks in when files are opened or saved to disk--was also very fast, completing a scan of 4.5GB of files in 4 minutes even, an above-average result. And its overall impact on system performance was the smallest among the antivirus packages we tested.

That speed is good, but all the speed in the world doesn't mean much if a security product doesn't effectively stop malware. And given NOD32's struggles, we can't give it our recommendation.