I would not use windows. I don't like having laptops twice as thick as they should be and the design of the OS matter greatly to me. If I'm going to be staring at it all day, it should be designed to look good (both the OS and the computer). I also like the built-in programs of OS X moreso than windows, such as Safari, Dashboard, Dictionary, Mail and more. I didn't switch because of viruses, I switched because I wanted something better.