[Closed] Help! How do I protect my new PC?

I have a new PC for my family to use. Norton is installed already and I have downloaded microsoft malicious software removal tool. I was advised to download zone alarm but then my computer didn't like having 2 anti virus programs so I have deleted this. Someone has also recommended the following, but I don't know how many I can install without upsetting the computer by slowing it down and wanting to shut down all the time!: spybot search and destroy malwarebytes highjackthis AVG antivirus (but I already have NORTON) Are these what you would recommend and how many would it be sensible to download? Many thanks for your help, Alison

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