If you haven't watched Inception, spoilers alert. If you haven't watched Up!, spoilers alert. For the rest of you, this Inception/Up! trailer mash-up will make you flip out. In the words of Mark Wilson: "holy shit that trailer is amazing."
It's good but it shows the power of music to set the mood in film. There is part of me that resents music in film for this very reason though. It becomes an audio command for the audience to feel scared, happy, etc . . .
I'm not saying music shouldn't be used in the movies but that movies are way to reliant on it. I still love that the Coen Brothers did not use music for "No Country for Old Men."