I'm personally very happy with my ZoneAlarm Pro/NAV CE combo (though I also have a hardware firewall... my ZA is just an extra precaution). I've used NIS before, but I wasn't very happy with it. Granted, the setup is fairly simple and maintenance is a piece of cake, with the automatic LiveUpdate, etc., but I just didn't feel that it performed how I wanted it to. Also, I did not like the log. I have one license of MCS ZoneLog Analyser I use over my network to keep track of all of my ZoneAlarm logs, and I feel that it does exactly what I want/need. I also tried some of Norton's enterprise firewall programs, but was not too thrilled about those either. If I were you, I'd just try out a few different firewalls and see what you like most.

AJ