Upper mc resisaizable

Hi to everyone, hope to explain weel about what I woul like to reach.
I use As2 and Flash cs3.

Well, I would like to develop a website, starting in flash with a Stage with these stats:

widht: 1000 px and Height: 674 px

Now, I need to divide this stage in 2 part: upper and lower side. Every side (upper and lower part) have height of 337 px (674/2).

Well, I need to make the upper part resaizable, because the mc will host a picture that, in resizing the stage, have to adapt it width and height proportionally and smoothly.

Maybe what I wrote will seem confused, but I hope that my attachment will explain better for me.

Thanks to everyone will help me…