Depends on what sort of security is in your mind. Do you want to protect against viruses/trojans or do you want security of personal info/location etc?
I used to subscribe to Norton but since the inception of Windows Defender, I haven't had the need to install any other third party app. It does a fine job of protecting my machine and yes this is my production workstation. I do have boot linux at times and Bit Defender does a fine job there, clamV is good too although with the integration of bash in windows 10, I'm hoping to ditch linux completely, I'm going to miss it but managing dual os is a drag.
Now if you are worried about your privacy or want to make it hard to be tracked, I suggest using tor browser, but keep in mind its of no use if you enable plugins such as flash etc, as long as you run it in its default state, you're good to go.
Any computer connected to a network is prone to viruses, yes it might be a bit harder to infect a linux distro but not rocket science and then there are rootkits to worry about. So the notion of "I'm secure cause im on linux is absurd"