Since some of you might not know… just a quick note to inform you :
Your Mac is not completely immune to viruses and malware (and never has been). The weakest link in the security chain of Mac-protection is often the user himself…
A program called “MAC Defender” claims to be your best protection, but do not install it ! If you really need a reliable virus-protection app for you Mac, go only with the renowned ones like Sophos, Kasperski, Norton, ClamXav or VirusBarrier (downloads available via MacUpdate.com, or from their respective brand’s websites).
MAC Defender is a fake AntiVirus-app ! It’s a trojan horse intended for phishing your valuable data, passwords and credit card info.
Apple has put info on how to avoid or remove MAC Defender online here :
…but still : best remedy is not to install it at all !