Shields UP
That link is a free testing service for your network from the Internet. It reports on your security, including port probes for vulnerability.
I posted that site because the firewall in my linksys router provides strong protection to my network without any additional firewall software. I have turned off the software firewalls and A/S works on my system just fine. For wireless security I have changed the SSID, stopped broadcasting it, changed the default password, use MAC filtering and WEP 128bit security, plus I have set DHCP to issue only 4 IP numbers, one for each machine that is connected by wire and one for my Ax wireless.
Just some food for thought.