BlackIce Defender is not really a "firewall!" It's a N.I.D...
ZoneAlarm has the ability to hide ones footprint on the net, this makes it harder for someone to shoot you if they can't see you 🙂
BlackIce has never been responsible for locking or crashing a computer it has been installed on (generally speaking), and uses very little resources 🙂
ZoneAlarm has locked and/or crashed a computer it has been installed on (5/7), and uses from 9% to 15% of Windows resources 🙁
BlackIce can't block an out-going packet 🙁
ZoneAlarm can block out going packets 🙂
These 2 programs might be marketed to the same group of users, but they are essentially different type of programs.
If I was on a dial-up (56K), I would only use BlackIce Defender.
If I could only use 1 program (BI or Z/A) for a DSL or Cable connection, I would choose Z/A.
For my needs, I use both and find that they compliment each other, I feel naked any other way 😱
------(Forgot to add)---------
Since the "heading" is firewall, lets not forget the "hardware" firewall approach. Currently I am only using the software version, but I think the ideal firewall would be:
Hardware firewall (Linksys, Netgear, ect...)
-- and --
BlackIce Defender
To me, that would be a perfect firewall for under $150!