Linux doesn't really require anti-virus protection. There are very few viruses for Linux because it's secure (i.e. even if a user downloads a malicious program by accident, it cannot do a lot of damage because it is limited by the strict access restrictions of that user; on Windoze, even the latest versions, virtually any user can mess up the whole system, despite the fact that the user may not have had any access to the entire system, it's much easier to bypass security on WIndoze than on Linux, it all boils down to that). The rule of thumb on Linux is the following: "as long as you keep your firewall and all your critical publically-accesible programs up to date, you should be fine".
The firewall that comes with Linux is really the only firewall for Linux (there's an older version, but it's pretty much the same idea and it's becoming obsolete by the minute, so stick with what you have on RH8). It's built into it at the core. In this case, it's really not which
firewall program you use, but it's how you configure
the firewall (be it manually or by using a program like the RedHat Firewall setup program/control panel). That's what really matters.
The firewall under Linux is very, very powerful (in fact I think the Linux firewall is one of the most powerful and advanced firewalls of all
operating systems). The actual name for the Linux firewall is iptables
(IP for Internet Protocol and Tables as in tables of filtering rules). The RedHat 8.0 firewall configuration program is fine for a desktop setup, but if you want to run a server, you really need to get a more powerful config program, such as gShield
purposes, I'd say that the RedHat 8.0 firewall setup program is quite allright. On the other hand if you really want to learn how to really
set up a firewall, you should check out gShield or just study the iptables command directly (I am giving you the options in the order of complexity