At least 6 Internet-facing machines running with Win 95 initially and on Win 7 today. No AV other than Microsoft Security Essentials. No viruses or malware ever activated in 22 years. That comes to over 30000 machine days, so it would require 10000 idiots downloading naked celebrity screensavers to get the claimed level of statistics. I don't for a moment doubt that there are ten thousand idiots out there, but I suspect there must be enough careful and savvy people around too that make the one per three days figure look almost as ridiculous as the wrath of the ASA. They'll probably just move to claiming 2 infections per week which is a different advert and will take the ASA over a month to respond to.
BT got stopped from claiming the most powerful Wi-Fi, so they've just moved to claiming the best coverage which is equally bollocks.