Virus protection is absolutely absurd.
I have had many computers, my current one I've had around 3 years, never a DAY it had an antivirus on it, and it runs as fast as the day I bought it.
My grandparents computer, has Norton, it's hardware is actually BETTER than this one, and NEWER, yet it runs around 30 times slower, and that isn't an exageration.
As long as you don't go to shady sites and download stupid stuff, or have a family based computer, using antivirus is stupid.
However you're Elecro, so telling you to be smart is like telling a dog it's a cat, so go with Avast!