Hello,
I know that NIS has a software firewall. However, wouldn't my wireless router?
If this is the case, then why would I need NIS (with the firewall) and not just AV?
This always confused me, lol. 
Ciao,
Flavio_C
You are correct. A router comes with a hardware firewall that will prevent any unsolicited incoming traffic. A two-way software firewall is for people who feel the need to be able to control which programs on their computer that are allowed to connect outwards. For protection, a software firewall isn't really needed for the normal user, but even if he or she doesn't use an Internet Security suite that comes with a firewall, the normal Windows firewall is as good or better than any third party firewall at protecting the user from attacks.
Further reading:
http://www.wilderssecurity.com/threads/why-you-dont-need-a-firewall-article.360176/
Hi Flavio_C,
I have to respectfully disagree with Bombastus: "a software firewall isn't really needed for the normal user"
Your router undoubtedly uses NAT (Network Address Translation) which acts as a preliminary firewall guarding against certain incoming requests.
The Smart Firewall in Norton products is a more sophisticated firewall.
The Norton Firewall can monitor applications on your computer as they request access to the Internet and block or allow traffic on a per-application basis.
Also, the Norton Firewall is a two way firewall, monitoring both incoming and outgoing traffic.
Finally, the Norton Firewall can protect your computer from other computers on your network if they should become infected.
In my opinion, the best scenario is to have a hardware (NAT) firewall working in conjunction with a software firewall installed on your computer.
I hope I did not oversimplify that, but you can read more here.
Hi Flavio,
Nice doubt.
Router fire walls are usually generic in nature, ie they are independent of connected devices.
.
Some thoughts:
Will you use only the wireless routes to connect to outside network (internet)?
What if you need to monitor your applications individually?
How will you restrict particular protocol or port of your PC from using network resources, whereas other devices can use the same port for communication?
What if the network attack originated from good network?
.
.
Most router fire walls are packet filters and statefull packet inspectors.
But firewalls installed in your pc uses more sophosticated technologies like deep packet inspection (DPI) and deep flow inspection (DFI) and unified threat management techniques as well.
Moreover there firewalls are more nearer to user and provide more security using latest evolving threat mitigation technologies without need for a hardware upgradation. .
Hope this clears the smoke of confusion.