I guess maybe I am beating this particular drum a bit hard, but I know a few Mac users and this is no longer just my hypothetical good computing hygyne advice. I really would hate for my Mac friends to find out the hard way that its not safe to play in the street. Following up on AdvisorBits: Welcome to my world, MacUser, I noticed today that there were mulptiple posts to the Incident Handlers Diary as SANS regarding the Apple security issues.
I thought the remark by Kevin Liston this moring bears repeating, especially since it basically echos mine.
In an effort to use as little hype as possible I only suggest that now is the time for Mac users to seriously consider anti-virus, personal firewalls, and safe browsing habits. It is the time for Mac sysadmins to develop strong patch management policies. This likely means that a Mac is no longer the no-brainer-choice for what computer to get for your parents.