i need help with rollover movieclips

I need some help with animated buttons/movies in Flash CS3.
Bascially what i want to do is to create an animated movie clip that will be my header image for a blog i'm creating for college.
The animation was created in after effects and exported as PNG images for transparent backgrounds. Easy enough.
But i want to animate the movie clip as a roll over. so as the mouse is hovering over the MC it plays the animation in a loop, but when the mouse is moved away it finishes the animation then stops. I have had so much bother trying to do this. I have a decent enough knowledge of actionscript and flash and made plenty of stuff before, but with this i'm stuck.
I've looked high and low for tutorials but none are what i need or do not work. I've tried everything from using button overstates (which only play the animation once then need clicked to do it again???) to using on.Rollover actionscript for the movie clip. Yet i have not had any luck.
Does anyone know how to do this. I would prefer to do it as a movieclip as the header does not link anywhere. It is just for show as the navigation bar will be seperate.
All replies are welcome

Anthony