Very Good Malware Blocking
In addition to the company's own internal antivirus engine, Qihoo includes licensed engines from Bitdefender and Avira. However, you have to do a little work to make sure you're getting protection from those licensed engines. On the Virus Scan page you'll see icons for a total of five engines: 360 Cloud Scan Engine, System Repair Engine, QVMIII AI Engine, Bitdefender Engine, and Avira Engine. The last two are grayed by default, with an on/off switch that appears when you point to the icon. For testing, I turned both on.
Qihoo 360 Total Security Essential is a distinct improvement over its predecessor, 360 Internet Security. It gets great ratings from the independent testing labs, and it did well in all of our hands-on tests as well. On the flip side, I found that it erroneously marked one of my testing tools as malware. And while the behavior-based malware detection didn't pop up any notifications about actual malware samples, it flagged two PCMag utilities as suspicious.
Panda Free Antivirus 2015 remains our Editors' Choice for free antivirus. I'm particularly impressed with the availability of remote-control expert remediation for any malware that slips past the antivirus. I found Qihoo support to be not nearly as responsive. Even so, with a little tweaking Qihoo might well join Panda at the top. It's certainly worth a look.