I saw that new mac ad they had on tv the other day. Kinda funny in how its more likely that there are no mac viruses out there because most of the programmers (good and bad) use a pc, prefer a pc, and get better performance out of a pc. Who would want to write a program for a mac (no sane person would)?
As for a more in depth view of this I would like to direct your attention here. I feel that this movie is quite informative