You normally get extra content about the films in question, so it depends if you like DVD extras or not.
High def normally works well for scifi and effects movies as well, and sound becomes clearer, so it depends on whether your entertainment system is advanced enough to demonstrate the...
Do they teach much about social enterprise, or social capital in the free market at the moment. It's starting to look like it's going to be a useful thing to know about in the near future.