I'm trying to start editing trailers with Windows Movie Maker (cause it's the software i'm most familiar with) how do I get the music out of certain scenes to keep the talking in the movie?

Well,

This is post-audio.... and its really just being clever with the audio channels.

From what I know... you have to isolate the dialogue, which in a 5.1 soundtrack would be in the centre channel, so you have to kill the sides.

I don't really know the logistics of doing it on programs... but I'm sure you can find something on the a dedicated audio mixing forum.

Windows Movie Maker is terrible for audio editing...well all editing actually, but you're right it's very easy and I used it for along while... First, you can only have two tracks running (whatever is on the video portion) and the audio you add to the video. There are ways around this, but they're annoying and give you a shitty result.

If you have video with audio on it and you want to add music and a voice over in post you'll have to have a lot of patience and clever edits. What exactly are you looking to do?