Had Nod32, it let in a virus
Had AVG, it let in a virus
Have had Kaspersky for 2-3 years, and never a virus
I know others who have had viruses while having up-to-date A/V. I got them to move to Kaspersky and I don't think they've had a virus since
(btw, I got viruses from browser exploits, not from being an idiot and opening attachments, etc)