var speed = 2;
var xdir = speed;
var lleft = 0;
var rleft = 0;
			
function MoveCurtain()
{
	lleft -= xdir;		
	rleft += xdir;
	
	leftcurtain.style.left = lleft;
	rightcurtain.style.left = rleft;
					
	if (rleft < window.document.body.clientWidth)
	{
		setTimeout ("MoveCurtain()", 1);
	}
}