If your running a lan or directly hooked up to the cable modem / dsl modem it is highly recomended that you use iptables/netfilter.
i beleive is the home. not sure tho. anyway, it has tons of info on how to get started, how to NATanize your lan and such.
It's definetly recommended. Without a firewall, you'd bee suprised what kind of dangers you can run into.