So much for the invincible Mac...
I'm a Mac user, too, but anyone who claims the Mac is "invincible" is ignorant, at best. I agree with Grouch. Anyone who downloads a pirated copy of software (iWorks, in this case) and then gives it permission to install itself on your Mac, is not really an example of a problem with the Mac's operating system, but more a problem with the user. It's like asking a convicted criminal to install a burglar alarm in your house because they offer to do it for free. Should anyone be surprised if "someone" burglarizes your home the following week and the alarm never sounded?
Besides, all operating systems have gotten better in the last five years so hackers have switched to easier targets. If you look at the top vulnerabilities now, applications like Microsoft Word, Acrobat Reader, or browser plug-ins like Flash, are the top vulnerabilities now, not the operating system like before.