I'm fairly good at distinguishing between what's a virus and what's not a virus. 99% of things are in the latter category care of fairly non-dubious web surfing habits.
The last time I got a virus was sometime back when Vista was the new kid on the block. I was searching high and low for a keygen for a really obscure program and I thought I'd finally found one.
Windows Defender was all up in my face like "don't run this, it's a virus!" and I was like "damnit Windows Defender, I want this key" so I ran it.
Lesson learned. Viruses don't infect PCs. People infect PCs.