I have only ever had 1 virus, (that I know of, if there were others they must have been good virus's, because they never affected me) I think that was in '98. On this laptop that I am using now I have Avast antivirus installed, and on my other laptop as well, never switched on any windows stuff, actually make sure it is switched off is my first move. Don't have any Firewalls installed or use any other virus, malware, etc etc stuff, never have. There is a firewall thingy or something in the router, don't know much about it, but it's there doing whatever it does.
My 2 music PC's are connected to the net, although it's just for the basic stuff that needs to be done, updating/installing any progs or plugins that do it from within, but they don't 'surf the web' as such, no Email or anything. I have nothing on them, no antivirus, firewall, malware etc stuff, but they do go through the routers firewall thingy. Any actual manual downloading or web browsing gets done on the laptops, then I just transfer any files over to the 2 PC's when needed.
That's the way I have always had things, I feel safe. But if I was to give advice, I would say get yourself a good virus scanner, maybe set up your firewall, but the way I look at it is if you are careful and don't go to places you know you shouldn't, don't go opening Emails you know nothing about, stay clear of cracks and warez etc etc, you are stacking the odds considerably in your own favor.
So go get yourself an antivirus, I can recommend Avast, it's free, or you can pay for the bells and whistles if you like, kick in your firewall, and use common sense when on the net.