You may have other operating systems like the linux distrobutions and Mac but really does the average user know how to use these operating systems, god no. I think once setup and training done people will know but then why hasnt this been done. The same reason why microsoft didnt make that download available.

They are a business to and want to make money, they quite successfully do it. Although i dont use MS products and instead run linux operating systems doesnt mean that most people can do this. Lets be honest people have grown up with MS it wont change for a long time. Vista will become the new standard, just like XP did when it was released