I was recently surprised when someone asked me what anti-virus programs they should be running. Note, he said ‘programs,’ not program, and that’s what he meant. He thought that if one A/V (anti-viral) program would do him good then two or three would be even better.
Ah…. no, that’s not how it works.
While it’s certainly true that one A/V program will catching something that another program might miss, if you add layers of A/V software to one PC, you’re asking for the two of them to clash with each other. The end result is a PC that will certainly run slower, and might very well stop working from time to time because of conflicts between them.
You’re much better off if you just get one good A/V program and keep it updated.