Actually, independent field testing shows that free anti-virus is as effective as paid anti-virus. There are even Linux programs that can be installed on a boot disk to scan Windows systems which work very well. It's not a good idea to run two or more anti-virus systems on the same operating system. But a boot disk runs your computer while Windows is shut off. Any way you look at it two sets of eyes are better than one, and a boot disk can find things that a resident anti-virus cannot. So use what you choose for Windows. Pay for it if it makes you feel better. But a Linux boot disk with anti-virus scanning for Windows can save your cookies. Of course that is free software and free operating system. Sometimes movies don't apply to reality.
But there is no perfect anti-virus system. Each round of independent testing ranks them differently because the situation is always changing day to day. Microsoft Security Essentials has been near the worst and near the best, depending on the specific time testing took place.
But the worst possible virus on your system is you! No anti-virus can protect your computer from you, deleting vital system files from your system, for instance. When Microsoft tries, by deploying watch dogs around protected system directories, program files and program files (x86) it just interferes with your legitimate use of your computer and you STILL find ways to damage your own system.
Of course, even with a hobbled system that fights your every attempt to use it, malware runs rampant, unhindered by the safeguards which keep you from installing Silent Hunter into a system protected directory.
In spite of malware's open field, you are many times more likely to do damage than any malware. If you considered Windows Update as malware, you would be reduced to second place.
I am so happy not to ever have to deal with Windows Update again!
If you are interested in the absolute best ways to find malware check out
http://www.howtogeek.com/187037/how-...tside-windows/ and
http://www.makeuseof.com/tag/live-cd...windows-start/.
The worst thing about Windows is that you MUST make a bootable System Repair Disk and never lose it. If you have a Windows Update SNAFU and are left with an unbootable system and didn't make a System Repair Disk, Microsoft's only solution is for you to buy another Windows license. You cannot download or even pay for a Windows System Repair disk, ANYWHERE. Microsoft is actively pursuing and taking down websites posting Windows System Repair Disk images. The Catch-22? You are not really encouraged or warned ahead of time, and when you find you need it you can no longer get it.
I use
Rescatux, which can rescue both Linux and Windows, restoring the MBR, rehooking the Windows installation to the startup routine, etc. This is all stuff Microsoft wants you to just buy another Windows License for. You know, if Microsoft is so engaged on bringing the entire weight of the court system to prevent you from fixing Windows, why don't you just migrate to Linux, where you are respected as the owner of your hardware with the unquestioned right to repair your system? How much abuse does it take to leave an evil corporation who no longer serves its customers, except for lunch? ( "The rest of the book
To Serve Man, it's... it's a cookbook!")