Don't be confused with security vs market share
A Mac is just a computer using a different code structure that that of a PC. A Mac's "security" is no different than a PC. The only reason that a Mac seems more secure.....unless you actually believe that the TV ads actually contain a single grain of truth......is that its' abysmal market share and little use within the business community makes it not worth the time / effort of most "serious" jerks to write the code to infect it. However, even given its miniscule market share, Apple issued (or is issuing) something like 50 patches this week (most regarding security flaws ?) so I've heard.
Just go to the Apple web page and check out all the patches regarding security that Apple has released this year......certainly NOT what it implies in its' ads !