Fire Wall Question

I recently upgraded to AVG8 from their free version. Evidently the new version includes a firewall. I have Zone Alarm Pro as my firewall already.

I started wondering about the implications of 2 firewalls and went to a popular board to see what people had to say. There seems to be a consensus that one should not run more than one firewall, but no rational is given (there is a quasi rationale given for having a hardware and a software firewall).

I would like opinions from this board - as I consider it staffed and read by a more professional group.

I do not think I have ever had a problem with ZA-Pro, but - who knows?

I shut down AVG8's firewall - which caused AVG to shout in protest.

My question is "should one only run 1 firewall product if one does not have a hardware router system"?

Any comments on AVG8 vs ZA-Pro would be appreciated.

Tom

I personally use sygate for my firewall. I use a router and sygate on all my systems.and my opinion about running more is WHY? Not to sound offensive but why would a hacker bother with a regular residential isp when the 12 yr old can try to crack Microsoft's firewalls.

One shouldn't run more than one version of either firewall or antivirus. Quite simply, they are fighting eachother. You can look forward to lockups, slow boot up and other problems unless you get rid of one or the other.

AVG has been protecting my fortress here for over 3 years with no problem.

for the rational explanation it is easy:
firewall work by inspecting all network traffic and letting go according to rules. 2 firewall means twice the work. To process the rules faster the firewall usually tried to load completely on RAM, so now you are using twice the RAM.
End results..2 firewalls, twice the RAM, and more slowdown on your network. Is it more secure? Not, it is as secure as the most closed firewall.
The best aproach is to have 1 firewall and select your rules carefully, only allowing what you want. I also make a reminder to check the rules once on a while (because I could have opened ports for a web server that is no running anymore, etc).
As for Antivirus, this is even more critical. Antivirus scan files on access. 2 antivirus not only will scan the same file twice, but also could create an eternal loop (imagine an infected file, antivirus a scans the file, and detects a virus, at the same time antivirus b scans same file, but it is in use, so it waits. Antivirus A cleans the file and releases it, antivirus b cleans the file again, but detect the file changed from before, marking the file for deep scanning. Antivirus A recognizes a change in the file, and queues the file again to scan, antivirus b scans the file and releases it, antivirus a scans the file again (and again the process could start, or end).
router and a software firewall are different level of protection, 2 software firewall are the same level.
Just keep whichever firewall you feel more confortable with, or move one to another PC.
I liked ZoneAlarm Pro as a replacement for Sygate Pro. I currently use only zonealarm free on my web PC (I have a web pc, a work PC and a game PC) all with specific use.

Thanks the responses are pretty much what I expected - it is good not to be too far off. I am going with ABG8 for virus and ZA-PRO for the firewall. I will be reconciled to AVG8's whining.

Thanks again

Tom