HELP! Flash motion tween with transparancy

HI everyone. I’m having a massive problem. Basically i’m trying to make a flash plant with motion tweened movements. I can do this fine, but this plant has to hav a transparent background because its being used as part of a project with severals layers (html, flash etc…) I’ve made the plant in photoshop and tryed saving the seperate parts as both transparent gif’s and transparent png’s. but when i come to making the leaves move they look really bad! the edge’s go all stepped and lumpy. Is there any way to solve this. Thought about higher frame rate (which i’ll try in a minute), have also tryed converting to a graphic and a movie. otherwise i’m stuck as i can’t save the leaves as jpg because i can’t get transparency :*(

If someone could point me in the right direction i would be most grateful.