When it comes to firewalls I like to know what is being blocked. Most of the firewall packages I see try to make it easy on the end user by having an easy to use interface. In doing so they lose a lot of functionality you get from doing things manually at the command line. I recommend you go read up on iptables and block ips/ports/packettypes manually on your own... you can get a sample firewall script that uses iptables from my site at www.sekure.us.
Click on the nerd in the bottom right corner then get it from the downloads page. You can read up on iptables at www.tldp.org
and by searching on google.com