On one hand, I've got to say the Rankin-Bass version of The Hobbit.
The Hobbit was the cartoon that started it all for me. I saw it and I thought -- Wow! That's cool! Then I read the book and then... well, you know how it might go.
Later, in junior high and high school, I saw the original Conan movie and The Sword and the Sorcerer.
Both of them had a big impact on me as a DM. Both were cheesy in their own way, but I really loved them at the time.