You need good security (maintaining of your OS, firewalls, and etc) if you want to keep people out of things you dont want people to see (other networks and etc). I think he was implying that you need to use a firewall to block people from exploiting the vulnerabilities in Microsoft's software (Windows). Which is true but as I said above you also need a firewall for you other Operating Systems you run. I run FreeBSD and I run a firewall. I actually have a 100MHz with 45MB of memory acting as my router and firewall. I'm also running NAT on it. NAT on FreeBSD is really reallly easy to use and configure. Took me like 5 minutes to read about it in the handbook ( http://www.freebsd.org/doc/en_US.ISO...book/natd.html ) and another 5 - 15 minutes to recompile and reboot. I'm running LimeWire behind NAT too. I just force my ip to my public address and it works. :]