G Data InternetSecurity blocked all samples in our real-world tests (which assess how well security software can stop previously unknown threats). It also spotted all but five samples in our “zoo” of 108,869 samples of known malware--the best score we’ve ever seen on this particular test.

In addition, G Data's package had a low false-positive rate, labeling only one known safe file out of a pool of more than 250,000 as possibly dangerous; you don't have to worry about it flagging a good file as bad. It rendered all infections on our test PC inert, and it removed all traces of malware 60 percent of the time.

This suite's impact on PC performance was fairly minimal overall, but it did struggle in a few areas. It finished our on-demand scan test (which measures how quickly a suite can scan 4.5GB of files when you tell it to do so) in an above-average 1 minute, 49 seconds, but its on-access scanner (which kicks in when you open or save files) processed 4.5GB of data in a slow 6 minutes, 41 seconds. By comparison, on average the products we tested completed those tests in 1 minute, 59 seconds and 4 minutes, 48 seconds, respectively.

The G Data suite added less than half of a second to startup and shutdown times as compared to a PC with no antivirus software installed--in both cases, the best result among the products we tested. It also produced a good result in our download test, adding only about 1.5 seconds compared to our test PC without antivirus installed. On the other hand, it slowed our test PC considerably when we loaded Web pages, installed software, or copied files over the network.

G Data's interface isn’t too impressive. Its installer is fairly painless, but it forces you to click through a number of screens and requires you to restart the PC before you can use the software. The main screen isn't significantly different from that of last year's G Data suite, which isn't a good thing. Reaching some commonly used features via the main control panel is difficult, since they’re often hidden in menus. And unless you’re an expert, the settings can be confusing--there are just so many of them. That said, the clearly labeled 'Correct' button that appears when a problem occurs lets you quickly and easily fix any issues that prevent you from being fully protected.

This isn't a perfect security suite, but the package excels where it counts most: stopping malware. If you can put up with some interface annoyances and sluggish scan speeds, G Data InternetSecurity 2012 is definitely a top-notch contender and worth your consideration.