Apparently if you are a user of Symantec's security software, and have not kept your software and virus definitions up-to-date, you have been vulnerable to Spybot -- malware that will use your computer in malicious ways. In November of 2006, Spybot (a varient of the original Spybot from 2003) started showing up on machines with Symantec security products; and a fix had been available since May. Clearly there is an issue with folks not keeping their security software up-to-date.
Unfortunately if you are a Windows user, your machine is much more likely to be under attack -- hackers looking for vulnerabilities. And the general user population just want to use a computer, not be a technology geek, which seems to be the requirement. I think it is worse than owning a car.
With a car, the buy-in cost is much higher, so in general terms, there is more recognition that maintenance is required. Further, there is an infrastructure in place to make it easy to keep up on basic maintenance. But in the PC space, the buy-in cost is much lower, but the cost of compromising your personal data is much higher. Yet people do not understand that just having an anti-virus software is not enough -- it must be closely monitored and maintained. It is also more difficult to pack up your PC and take it in for work compared to your car. And because of that low buy-in cost, people are less willing to spend money for the maintenance.
So what should your average user do? Though not completely impervious to attack, the Apple platform is much more likely to offer the security protection required. Again if you look at cost, yes you will pay a bit more (entry level is actually only $599) to get a Mac with all the productivity tools that you use on Windows, but your total cost of ownership would still be considerable less than if your machine was compromised.
Finally you might ask, "Do I use a Mac?" Well, I have, but not since 1999. But remember, I am in the niche group of technology geeks. And with Apples move to the Intel platform and the maturity of Parallels and Boot Camp, it looks like I will be returning to the Mac on my next purchase.