Use one or the other. Running 2 firewalls will / may cause problems, not to mention that you only need one firewall. I used Mcafee free firewall for a while from Aol, but now use Zonealarm, as I prefer it.
Go with Zone Alarm and AVG Both are good, low on demands and free.
Aol was the first thing I tried for an internet connection and have stayed with it ever since. Good reputations are hard to make and an be easily lost!
Long before internet access I picked up the stoned virus from a floppie, and Dr Solomon saved the day.
Dr S was taken over by McAfee who virtually lost interest in helping me with the last months of my contact and was at the time difficult to remove. I migrated to AVG and have not had an infection since.
Can I put a word in for McAfee? I think it is as good a firewall as any and gives you access to the HackerWatch org. maps and traces if you are interested in such things. Is it updateable? I don`t think so, but you can add addresses that you know are dodgy. The McAfee site seys the (AOL) version is no longer supported but that is hardly surprising. Use one firewall only, of course.