BitDefender's installation process is a bit longer than that for most of the antivirus products we looked at, as it takes you though not just installation, but various setup options as well. BitDefender comes with three interface "tiers"--a Basic interface, an Intermediate one, and an Expert one. The idea is that you can use an interface that fits your expertise level; the higher up you go, the more options you'll have access to.

I have mixed feelings on this approach: I like the basic interface for its simplicity and directness, and the Intermediate interface isn't bad either, but the Advanced interface is a convoluted mess of tabs running across the top and along the side of the window. If you're looking for set-it-and-forget-it simplicity, stick with the Basic mode. If you like toggling knobs and buttons and aren't intimidated by lots of tabs and controls, give the Intermediate and Advanced modes a try.

While BitDefender wasn't the all-around winner in malware detection and removal tests, it still put up some very good scores. When detecting malware using scanner-based detection methods, BitDefender Antivirus Pro detected 97.5 percent of samples--a solid score, although the top performers in this test detected over 99 percent of samples. This particular test mainly determines how well a product can detect known malware.

BitDefender has an Achilles' heel, though: Antivirus Pro didn't do a great job at blocking actual, live malware attacks. It fully blocked 68 percent of attacks, and partially blocked an additional 20 percent of attacks. BitDefender wasn't the worst performer in this test, but it was definitely below average; most other paid antivirus products we looked at fully blocked at least 80 percent of attacks. This indicates that it may have some difficulty catching brand-new malware for which a signature file doesn't yet exist.

On the other hand, Antivirus Pro was one of the best performers at cleaning up an infection once it gets into a PC; it detected all infections on a test PC, removed all active components of infections in 80 percent of the cases, and fully removed infections 70 percent of the time--the best score among the products we looked at. In addition, it was one of the few paid antivirus products we reviewed that didn't flag a "safe" file as possible malware.

Malware scan speeds were around average: It scanned 4.5GB of files in 2 minutes, 6 seconds using the on-demand scanner that kicks in when you manually initiate a malware scan. The on-access scanner that checks files for malware as they're opened or saved to disk was somewhat slower than average; it scanned 4.5GB of files in 5 minutes, 27 seconds.

Antivirus Pro had a moderate effect on PC performance in our tests. The test PC booted in 46.4 seconds with BitDefender Antivirus Pro installed, versus 40.1 seconds with no antivirus software installed. But this is around average when compared to the other paid antivirus products we looked at. This trend continued in other tests that show how antivirus software impacts overall PC performance--BitDefender scored either a little above or slightly below average for products we looked at in most of the PC speed tests.

Every product has its strengths and weaknesses. BitDefender Antivirus Pro 2011 is a pretty solid package, with a healthy set of features. But while it did a very good job in most malware detection and removal tests, you should bear in mind that it may not block brand-new malware attacks very well.