You really can't go wrong with any version of SF2, they're all great. Also you can always purchase other versions down the road if you'd like and merge them into one install (that's what I've done). Unfortunately windows 7 is what you need, and I think the cheapest you can find it anywhere is 90 dollars for the basic version. However it is well worth it in my opinion, and I myself had to save money for about five months to afford windows 7 on my salary, however it was 180.00 for the basic version when I bought it almost two years ago, so it will probably not take as long now as it did then to afford it. But you won't be sorry, they are all great games!