Are you forgetting 50% of the reason for buying a Mac - OS X? Some people just do not want to deal with Windows anymore with all the bugginess, crashing and viruses. Even I as a lifetime Windows user have to admit that fonts are drawn better in OS X and the overall UI is more consistent.
I agree with maflynn here. W7 has really improved experience comparing to XP and Vista. I never even installed Vista but have been running XP in both 32 and 64-bit flavors for many years. As one of my systems runs OS X and 2 run W7 I must they both have strengths and weaknesses. I won't go into severe detail here as it would take a while but let's just say they're on par with each other for every day usage by most people.