FW come down to your own personal choice I normally use Iptables that comes with Linux but there are other u may try and use goto a the following site http://sourceforge.net/
and do a search on FW.
When it gets to virus software there r a few that I know like panda, F-Prot etc but let me give u a break down on viruses for Linux. Iḿ not say that linux is not pron to viruses but it is not as venerable as M$. The reason being is that in linux the user is not running as ROOT
this means that he can only cause damage to his own /home dir. and will not effect the rest of his system that is why itś important not to run as ROOT
only when necessary. .eg say u receive a email to view this file u have to detach it then maybe to execute it u have to chmod the file with x then u may execute it, while under M$ with outlook and Explorer it has bugs that allow this to happen automatically.
After this explanation I can conclude that it's not necessary to have anti virus software under linux unless u running a Samba server which shares files to other M$ box's or if u sending emails and want emails to be scanned before sending then yes.