You need to realize that people find security in price.
Will you wear a pair of jeans you get free from someone off the streets? Maybe... but the majority of the people will not. Will you wear the 80$ pair of jeans you bought at Van Heusen? Of course.
Linux needs to win on all levels, not just "Free"... once the "FASHION" of linux hits, then the corporations will feel secure. Security in numbers. Once a few fortune 500 companies do it, the bricks will begin to follow suit, and microsoft will lose footing.