Stulid listed the reason above really. Personally, I like my cards running at the same bandwidth. Another is the utilities on the board itself, along with its aesthetics, black finish, along with a black back plate fits the case.
If you are a student you can get Win 7 fairly cheap. If not, that will push your budget up a little.
If you are a student you can get Win 7 fairly cheap. If not, that will push your budget up a little.