Javascript - menus in motion

[artsapimp]

I am trying to create a function that sends the current div off the screen (left=700 for testing) and then move the next div onto the screen (left=200). I am very close but am falling short when trying to assign a value to a function (eval). Any help would be great appreciated.

< script language='javascript' >
var curActive = 'Sec0';
var nextActive;

function setActive(SecID){
	nextActive = SecID;
	LoopOffScreen(curActive);
}

function LoopOffScreen(SecID){
	if(parseInt(eval(SecID + '.style.left,10')) < 700){
		eval(SecID + '.style.left') = parseInt(eval(SecID + '.style.left,10')) + 1;
		setTimeout('LoopOffScreen(curActive);',1);
	} else {
		curActive = nextActive;
		LoopOnScreen(curActive);
	}
}

function LoopOnScreen(SecID){
	if(parseInt(SecID.style.left,10) < 200){
		SecID.style.left = parseInt(SecID.style.left,10) + 1;
		setTimeout('LoopOnScreen(curActive);',1);
	}
}
< /script >