You don't purchase CS7, It is a subscription , you pay by the month or yearly and you pay and pay and pay - but never own.
One thing for sure, it is not Photoshop 6 or Photoshop 7. I used Photoshop 5 then Photoshop 7 before CS 1, 2, 3, 4, 5, 6 came on the market. There is a difference.
Thanks for clearing that up it still does not change anything.