Macs and Viruses: Myths Debunked
However, Macs are not easily infected because it is a variant of Linux, which means that Mac applications are self-contained, and does not have to hold it settings in a central repository, such as the Windows Registry.
There are people who have written virus code for the Mac OS operating system, but viruses are much less effective, and much easier to remove that their Windows counterpart.
If Microsoft wanted to really make their operating system more secure they could release an operating system that does not use a registry, but instead uses XML files. This move alone would render current viruses ineffective.
Securing Windows might make since to the user, but it means a lot of lost income to the likes of Symantec, McAfee, Computer Associates, Best Buy, AT&T, and others who either attempt to keep viruses at bay or support you in your virus removal efforts once you have been infected.

