[mad2moons]

I prefer tiny personal firewall. I used zonealarm ages ago but didn't like it, can't remember why now...doh But i always advise friends and clients to go with tiny

[Avalanche]

I like Sygate Personal Firewall.

It is also free, and offers just as much, if not more control over traffic as ZoneAlarm, but it hasn't caused me anywhere near as much hassle as far as conflicts or just plain not working right.

The only thing about Sygate that I think could be improved, is the systray icon, it's too basic. I really like the traffic meter ZoneALarn has, it's a great little touch.