If your router supports it, I highly recommend you go the DD-WRT route. It adds functionality that manufacturers don't want you to have with the stock firmware. I personally invested in a Linksys (Cisco) E3000 and have been using it with DD-WRT for years. Learn a little iptables syntax and you can configure it to firewall your whole network.
Never ever plug a computer directly into your provider's modem. You're asking for trouble.
Thank you for your #13!