Plus don't forget ... If you DO get a virus or spyware, you can install antivirus software, scan, clean, and uninstall. They do their job, but having them on 24/7 is the part that I cannot deal with as it severely affects day to day operation due to constant scanning.
I am a programmer/tech consultant but my friends and family just think I am the IT guy, so I get to fix their computers. Often people complain to me that their PC is running slow. Funny enough, even with antivirus installed, they will still have some spyware that their antivirus cant clean.
I clean it with Prevx and then uninstall their virus software, and just doing those 2 things makes their PC run like new.