Note there are individual security products (like anti virus or firewall) and there are interent security suites that do everything.
There are free versions of most security products so you could put a selection of those on, like Avast anti virus, Zone Alarm firewall, Malwarebytes for spyware etc.
But if you want to buy a full security suite then it is difficult to pick just one as each have their strengths and weaknesses.
PC Pro did a review of some security packages a few months ago
http://www.pcpro.co.u...ews/internet-security