I have a 4 port router to share my ADSL connection which claims to have a built in firewall. My friends advise me that I should be running a firewall to monitor inbound and outbound network traffic and so I have installed the free version of Zone Alarm. This warns me when any software tries to access the internet so that I can choose to allow this or not. However do I really need a software firewall, should I be able to configure my router to do this for me? Is it that one needs both hardware & software firewalls? Maybe I don't really understand what it is I really need, any help would be very welcome.