Flashback is the exception that proves the rule. As much as I like to disagree with people who suggest that the OS X is "fundamentally more secure than windows" (it really, really isn't) - it does tend to have many fewer active exploits than Windows Platforms do - and your average OS X system is much less likely to be loaded up with malware than your average Windows XP system.
Perhaps, but I find it unlikely that professional companies would let their workstations - Windows or OSX - get loaded with malware. In fact, I hardly encounter exploits or malware on PCs nowadays, and never at all in the few corporate environments I've been in.
