Have you gone to NaviX, go in and the last 24 hrs then near the top are some 5.1 movies. Try them and see if they work.
I've noticed over the last few months 5.1 movies are getting harder to find, I think because most people now get sound bars as one speaker looks better then a 5.1 set up.
I've got a 6.1 set up and its been set up for Sacd and dvda as I'm a music lover. Sounds great with movies too.
Dave