Helpful Links Regarding Malware Protection
An excellent link to read is Tom Reed's Mac Malware Guide.
Also, visit The XLab FAQs and read Detecting and avoiding malware and spyware.
See these Apple articles:
If you require anti-virus protection I recommend using ClamXav.
How can I check if I have malware on my imac?
As long as your OS X 10.8.4 is fully up-to-date, you paid attention to any warnings it gave you and you didn't disable GateKeeper then you are fully protected against all currently known malware. If you are having issues with your computer, describe them and don't automatically assume it's malware. It rarely is.