Ordet is quite good, damn near Dreyer's best. I can't see any reason to not watch any movie (other than lack of quality). I mean the toughest film I ever watched was Stan Brakkhage's The Act of Seeing With One's Own Eyes. The film was basically a 40 minute autopsy and it was extremely unsettling, because unlike hyper stylized gore fests, this is an actual documentation of autopsies, and seeing real corpses cut up on film just seriously bothered me.
Now if there was a film that was filled with animal torture, I'd probably avoid that at all costs. If you check out Altman's most recent A Prarie Home Companion, that might help you ease into Nashville. Nashville isn't really just about the country music scene, it deals with a lot of timely issues of politics and a lack of connection in modern society. It'd be in my top 100 and I still find it sublime.