100% Height Trick

Anova Design is a great example of this: http://www.anovadesign.com/main.html

I need to duplicate this height trick for a site I’m designing, I’ve seen plenty of 100% width and height threads but nothing discussing this particular technique. My thoughts on this are a single flash file that scales to 100% height acting as the background (not the gradient, the elastic white background) with another mc loaded on top, but I don’t think that will work without the second mc being stretched vertically as well. Anyone have a solution to this?