First, the good news: McAfee's suite does very well at detecting malware before the attacker infects your PC. It fully blocked 96.2 percent of brand-new malware in our real-world malware-blocking tests--a slightly above-average score compared with the other suites we looked at this year. Meanwhile, its 99.99 percent detection rate for known malware samples was the second-best result we saw this year--and ever, for that matter. Its three false positives (out of a pool of 250,000 files) wasn't the absolute lowest we saw, but it was still very good.

But although McAfee's suite put up a good showing in those tests, it was another story once malware got onto our test computer. The McAfee package detected 80 percent of active infections on our test system, a below-average result--only one other 2012 suite we evaluated was unable to detect all infections in this test.

In addition, the McAfee product rendered malware infections inert just 70 percent of the time--the second-lowest showing in this test. By comparison, 9 of the 14 suites we looked at successfully disabled all infections on our test PC. That said, McAfee's suite was able to eradicate all traces of infections 60 percent of the time--a slightly above-average result among this batch of suites.

McAfee's suite struggled in some of our system-speed tests, producing a greater-than-average impact on overall system performance. It especially struggled in our application-installation test, and when we copied files over a network. It added over 1.5 minutes to our app-installation test (as compared with our test PC with no antivirus installed), which was the second-worst showing in this test. As for network file copying, it tacked on nearly 2 minutes to the test, a result good enough for only eighth place.

Scan speeds weren't great, either. McAfee's on-demand scanner (which runs when you manually start a scan) took 1 minute, 51 seconds to check 4.5GB of files, placing tenth overall for this subcategory. Its on-access scanner--which runs whenever you open or save a file--disappointed as well: Its time of 7 minutes, 4 seconds was the second-worst outcome we saw in that test.

All that said, we like McAfee's interface. The suite's installer takes a few steps to complete, but it has a couple nice touches: It will check your PC for malware before you install, and it will download the newest version of the software before it begins installation. The update check will take a while over slower connections, but it's a welcome addition nonetheless. For the most part, McAfee's main control panel is easy to use--clean, uncluttered, and friendly.

On the other hand, the fact that the firewall asks you to decide which apps to allow or deny Internet access is not very user-friendly, and strikes me as a holdover from the days when it was okay for a security suite to be difficult and annoying to use.

Should you buy McAfee Internet Security 2012? Although it didn't do terribly overall, and although it offers some things to like, we find it difficult to give this package a recommendation considering its low ranking. But if McAfee can smooth out some of the rough spots, the suite may be worth watching.