ActionScript 2.0 :: Align Stage To The Left?

I want flash banner to span acros the screen so I put width="100%" and Stage.scaleMode = "noScale"; ok. But, this way all its content is centered. I want it to stick on the left, and so I put this code in it:

Code:
onEnterFrame = function () {
_root._x = 0.5 * (750 /* original document width */ - Stage.width);
}

This works. But the way this thing works when I resize browser window is far, very far from smooth. I tried to change it to

Code:
onEnterFrame = function () {
var rx = 0.5 * (750 - Stage.width);
_root._x = rx + 0.1 /* or another number */ * (_root._x - rx);
}

I am wondering if there is some straightforward way to do this, like some hidden FLA setting, or some Stage/_root property, and if there is no, how the hell to script it?