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Honestly, for some time the security software from MS has been "good enough" for most people. Then again, there's plenty of people that will click "OK" to just about anything that pops up... which is why when one of my grandmother's PCs finally died, I bought her a chromebook... best option for those not technically inclined.

None.

grsecurity (Well, Open Source Security, Inc.) is a good example of an actual security vendor.

Microsoft

Microsoft has by far the best AV product (from a code quality aspect, at the very least), but I'm not sure if it qualifies as a vendor in this context. After all, MSE is essentially free.