Alpha Fade In and Out w/Actionscript

I would like to fade a movie clip in when you roll over a dirrerent movie clip and have it's alpha stay at 100 until you roll over another movie clip, at which point it's alpha fades back to 0.

I am using this for a menu:

EX:

About Us - MC to roll over
[company people news] - MC to fade in

and then when you roll over another menu item this menu's submenu fades back to 0.

THANKS!