Keith has Norton AntiVirus, Malwarebytes' Anti-Malware, SUPERAntiSpyware, Windows Defender, and Windows Firewall. Is this overkill?
That depends. If you have all of them running at all times, that's very much overkill indeed. The general rule of thumb is that you need two always-on security programs constantly operating in the background: an anti-virus program and a firewall.
The antivirus program checks every file you open or download for malware. The firewall controls what comes into your computer over the network. A good one also controls what goes out.
Sometimes one program handles both of these functions. That's a security suite.
If you have more than one antivirus program running at the same time--or more than one firewall--you're asking for trouble. Two such programs, trying to do the same thing at the same time, will slow down your system. Worse, they can cause conflicts.
Norton AntiVirus and Windows Defender are both real-time antivirus programs. You should remove one of them.
But it's a good idea to supplement your firewall and remaining antivirus program with one or two on-demand malware scanners. These are similar to antivirus programs, except that they don't operate in the background. Instead, they scan your hard drive when you tell them to. The free versions of SUPERAntiSpyware and Malwarebytes' Anti-Malware make excellent choices in this area. They're the ones I use.
Contributing Editor Lincoln Spector writes about technology and cinema. Email your tech questions to him at firstname.lastname@example.org, or post them to a community of helpful folks on the PCW Answer Line forum.