I would recommend this article about how expensive the Mac is compared to similar machines. https://technologizer.com/2008/10/19/is-the-new-macbook-expensive/ it is 15 months old but it is still applicable.
Now let the arguments begin on the operating systems....
An interesting comparison ; but 15" is more of a main stream PC laptop size which probably would have biased the out come towards the PC.
And as cjl said 15 months is a long time in the market today.
And so far Win 7 seems a heck of a lot better than Vista.
Al