Maybe there are extra packages for spss that do this for you, but as i am not familiar with those, here is what I would do:
1) save a copy of the data file holding only demographic information using copy dataset and delete variables command
2) in another copy of the file (i like copies, makes me feel safe
), use restructure to restructure your data in the way you suggested. you can just follow the steps in the menu, should be easy enough!