TopDawg, if your system is on all the time, and connected to the internet, worry about your firewall first. Prevention is easier than detection and elimination.
Also, any software needs can be taken care of at SourceForge, or the GNU homepage... Free, open source, software is less likely to contian virii or have security flaws. Also updates to vulurabilities happen faster than with large companies, but you din't get the same kind of update serive with most Open-source code and little to no tech-support.
Just my 2.0 x 10^-2 USD.