Applieing sound to buttons and movieclips

I have a movieclip that is acting as a button. I want to apply a sound to it but Im not exactly sure how to go about this. I am using a HitTest and making it go either to the PrevFrame or the NextFrame depending if I am rolling over the movieclip or not… Any way, should I use some sort of AS to play a sound clip on an onRollOver or should I insert the sound clip in a frame?

Also, does anyone know a good site to get free sound bytes that are good for Flash sites? Thanks

Mike