You are very welcome.
Everyone seems to have varying opinions as to which is best, but in my opinion, one cannot beat ZoneAlarm. Like I said, I don't use the free version but I am sure as far as stopping intrusions into a computer go, it is the same as the one that comes with the paid antivirus program. The one that comes with the antivirus program has an operating system firewall, which I don't want to be without, that I don't think the free version has. I have used ZA antivirus/firewall for many years, on many different computers and as long as I can afford to pay 20 bucks a year to renew it, I will always use it.
I do not use the latest version of it because I have not upgraded to SP3 and it requires you have that for the latest versions, so I just stick with the latest one that does not require that and am very happy with it.
Comodo is suppose to be a very good firewall, it also comes with antivirus that one can install, or not, and it is free. Off the top of my head, I cannot think of another free one out there but I think there are a couple more. Others can probably give you some ideas on those. You can also check out the AntiVirus, Firewall and Privacy Products and Protection Methods section of this forum for ideas and opinions on that. Here is a link to that section of the forum in case you need it.http://www.bleepingcomputer.com/forums/f/25/antivirus-firewall-and-privacy-products-and-protection-methods/