OS X is safer than Windows, due partially to obscurity, partially to design. That being said, it is NOT 100% fool proof. The best defense against nasty things has always been and will always be the user's behavior. This is true on Windows or Mac. Do not click on links that people send you (especially if you don't know the person that sent it). Do not open attachments from people you don't know. (Especially .exe, .bat, .zip, .doc, .docx, .xls, .xlsx, .rtf and .DMG files)