I just watched The Rescuers Down Under with my kids the other day. I hadn't seen it since I was about 10 years old. You're right; it's downright terrifying in several places. The main villain is truly a BAD guy; no regard for life, hateful to his own pet and actively tries to kill a kid for the last third of the film.
But I'm glad we watched it. Part of my childhood was being shocked, scared and sometimes even scarred by movies. Perhaps it was because I watched some of them at too young an age, I don't know. But at the same time, they left an indelible impression on me for life and in some small ways helped shape me. I'm not trying to scar my kids, but I don't want them to only think of the world as a smiley, bubbly place; it's also a place of danger, mystery and fear.
The most important thing I've been learning as a parent is to talk to your kids after or even sometimes during the movie and not just let them sit there and absorb it with no discussion.
This has been a turning point for me in watching films is having kids. While I won't shy away from films that I would have watched before becoming a parent, I certainly am more choosy about what films I watch because I want to be able to take the time with the kids and talk about it. Even simple discussion points can be meaningful.
And yeah, Disney had no qualms about villains getting gruesome deaths. Here you go: http://www.cracked.com/article_16795_th … eaths.html
Also, my daughter fairly recently watched Rescuers Down Under and it is still one of my favorites. George C. Scott, now that I know that it is him, is great as the villain, but is truly villainous. John Candy is fun too with some great one liners.