I use Mathematica for computations and simulations-- and making pretty pictures. So is it worth it to purchase Mathematica 7.0? Or should I stick with 6.0? From what I have seen and heard, Mathematica 7 incorporates a lot of image processing features that are pretty neat. How about computation and simulations? Are there any noticeable differences between 6 and 7?--new features? Any input appreciated.