Is it true that having more than 1 firewall will result in both firewalls competing with each other?, because it's basically just like having more than 1 spyware / anti-virus scanner isn't it?
you should only use one firewall. the difference is things like spyware scanners are passive and only scan when you tell them to. a firewall is active and is constantly "making decisions".
A hardware and a software firewall is fine but two software firewalls is gernerally concidered a bad idea and could even leave you more vulnerable to attack, apparently.