I have ZA and have just had it probed by Shields Up! The result?
"Your system has achieved a perfect "TruStealth" rating. Not a single packet — solicited or otherwise — was received from your system as a result of our security probing tests. Your system ignored and refused to reply to repeated Pings (ICMP Echo Requests). From the standpoint of the passing probes of any hacker, this machine does not exist on the Internet. Some questionable personal security systems expose their users by attempting to "counter-probe the prober", thus revealing themselves. But your system wisely remained silent in every way. Very nice."
I don't update ZA on the grounds that the earlier version is still working just fine. I am using version 6.0.667 and I keep that version for installing on other machines. I don't suppose it will work on Vista though.