BleepingComputer.com: Modem/Router Firewall

I have a DLINK wireless ADSL router DSL-G604T, which I understand has a built in firewall. I have looked in the routers settings and it says Firewall Enabled. I am also using Comodo firewall, but am wondering if I need this as well as having the routers firewall enabled? Do I need both? Is the routers firewall sufficient on its own? If I do use just the routers firewall, do I need to configure it for optimum use? I am using Vista and Firefox. I mainly use my computer for browsing, email and internet banking. Thank you.

I certainly advise using both firewalls, as each can achieve things the other cannot.

The router firewall has no way to take control of and monitor your computer's ports, or the behavior of software running on your computer. A good software firewall such as Comodo can detect outgoing packets that appear to be legitimate (ie they will be accepted and passed by the router firewall), but have a questionable source (eg an application that has never sought a connection before or has changed since it last connected, or code that is running from within an application but doesn't belong to that application - code injection- suggesting an infection). It can then block the requested port and ask permission to allow the requested connection. However a threat such as a virus can attempt to shut down a software firewall, but has no way to shut down the router firewall, as that firewall is not running on your computer.

So an external firewall such as that in an ADSL router/gateway is a difficult-to-compromise barrier to intrusion, but it relies on your computer giving it uncompromized data to begin with. The addition of a software firewall makes it much harder for any kind of malware to generate compromised data that would appear to be genuine and hence fool the router firewall.

Hi Platypus, Thank you for your quick, logical and easy to understand (for a noob like me) reply.
There was no real reason why I wanted to stop using Comodo, I just enjoy tinkering and trying out new things with my computer. I had read somewhere that some people only use the routers firewall and figured I would check out more about doing that as well.
I will heed your advise and leave everything as it is, especially as it has worked well for me so far.
I hope you have a great Christmas and a hot, sunny New Years. We are hoping to do the barbie at the beach thing this year so fingers crossed for a nice day.
Thanks again.