Yes Cyrax, Linux does have firewall and AV software.
Linux comes with a load of inbuilt stuff (namely iptables and suchlike) for simple software firewalling (but since I have a hardware firewall now, I tend not to bother with them as they suck up CPU cycles), and some companies, like Mandrke, make special "security" editions with enhanced security features (namely - runs less services, and runs as little as possible as root) designed to be installed on your gateway (namely a junked PC you put between your notwerk and the internet, in order to block unwanted incoming and outgoing traffic).
Virus scanners are hard to come by, but there are plenty available. Some things you need to bear in mind:
There are very few linux viruses out there
Linux is inherently less prone to viruses than Windows due to it's modular nature (as are most versions of *nix)
Most of the AV software out there is very expensive, as it's designed for mission critical hardware - namely webservers etc etc. I have a student copy of Datafellows F-Secure (Windows and *nix edition) which I'm going to install once I start running a webserver and other promiscuous net apps.
BTW, for all you out there who may know someone who paid for Exchange server, I laugh in your face.
P.S. I've just looked on Netcraft and have just seen that out webserver (the work one, running Apache on Linux) has an uptime of nearly a year. I rest my case
