Firewall: PCTools Anti Virus: Avira Malware preventer: Spywareblaster Malware scan/ remove: Superantispyware and Malawarebytes. Only have one anti virus. Others here like Avast or MS Security Essentials - all free
Some say AVG clashes with ZA etc.I used it until about a year ago .
I like Avira and it has definitely stopped a couple of attacks.