I don't see anything about a specific firewall in this only general terms. Also the reason for a firewall is not to deal with Dos or DDos Attacks, though in general one may see one time to time. Misconfig a firewall and it is usless, but my main reason for a firewall is to control the type of activity in coming and outgoing. Another tool to manage network capacity and what functions it may have. The IRC Dos thing has been around years and is nothing new, firewall can be very simple or complex, can they defen against Ddos well yes if configed right just like a router can. Me hardware/software firewall, and it is needed as much to keep the garbage from getting in and from my users from doing something stupid. Even in general terms for newbies I'd say research well before you make a choice, and ask people you know who have firewalls and how they use them.