Every time I see Dropbox on the front page of HN I think about this[1] all over again… 1: https://news.ycombinator.com/item?id=8863
That thread is hilarious, especially the first reply.
In fact, one of the best things about Dropbox is that they worked very hard on removing any barriers, including making sure that it can be installed on a windows machine without requiring administrator privileges.
I am confident that a large percentage of their users would have been unable to use Dropbox had this issue not been addressed.