I feel MAC is faster then windows because of its more efficient OS.
Windows is faster when new and then performance degrades over the time because of windows registry getting bigger and bigger. Somehow mac maintains that consistency in performance.
When you go for windows then only software is Microsoft, not hardware like keyboard, monitor screen, mouse, power units etc etc.
High quality graphic cards, some great software utilities like time machine, iMovies, garage band etc comes standard.
Adding above two things justify the high cost of MAC. In-fact if you buy high quality graphic cards, and extra efficient softwares for windows then MAC cost is justified.
The flop side with mac is that you can't expand much in future without spending heavy amount on accessories.
There service plans are costly.
Buying MAC means you might end up getting into a tunnel where you will need everything from apple store, you will end up in the monopoly market of MAC.
Of-course, you will miss lot of internet freebies which work fine with windows.