I have been working with computers for 30 years at work and now that I am retired I am on it more than when I worked. I was a data base administrator and a lot of virus protection programs are free with your internet connection web sight and they work nicely if you do not down load a lot of shareware or free programs.
I hate Norton as it slows your computer down to a craw when it runs and many have had computer crash problems with it.
Cleaners are different they clean out registry files and some temp files They really are not as much help to computer response as they advertise and you can do the same thing with you window programs. I don't like them because they erase all the web sights you frequently use and you have to do a search to get back to them. Just remember the old saying if it says free their is a catch to it somewhere. JMHO