What did you make the files with? I find it strange that QT won't play it back natively.

You should be able to use Handbrake to transcode the audio while mostly keeping the video the same. Then you can drop it into the DVD program of your choice.

I use Toast to write out video DVDs mostly. iDVD is more for authoring menus and fancy things like that - you don't get to store much video at all on a DVD with it.