They tell you why you might want to switch or add a Mac....and with respect to malware, an entire cottage industry was constructed around the demand for detoxing Windows PCs....not the same for Macs. I can do anything on my Dell that I can do on my Macs.....the difference lies in how it gets done, and what I (as the user) think of the look/feel/process.
Windows 7 seems to do a real nice job of coating Vista with a better grade of lipstick. The current hype around '7' is a little over the top, imho, for what you really get.....opinions will vary.