I tried ZoneAlarm a few years ago - it works, but the nagging is horrific if you don't go on and buy the full version. It wasn't worth the aggravation. Either buy it or something else, but don't bother with the trial version - it's annoying.
I think we've had this conversation before....................... I would not recommend ANYONE surf the net without a decent SW Firewall/Security Suite that's even with at Router and using NAT. More than enough security white papers on the issue to kill a cyber rain forest.