function opacity(id, opacStart, opacEnd, millisec) {
    //speed for each frame
    var speed = Math.round(millisec / 100);
    var timer = 0;
	if(opacEnd != document.getElementById(id).style.opacity)
	{
		//determine the direction for the blending, if start and end are the same nothing happens
		if(opacStart > opacEnd) {
			setTimeout("document.getElementById('" + id + "').style.display = 'none'", (100 * speed))
			for(i = opacStart; i >= opacEnd; i--) {
				setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
				timer++;
			}
			
		} 
		
		else if(opacStart < opacEnd) {
			if(opacEnd == 100) document.getElementById(id).style.display = "block";
			for(i = opacStart; i <= opacEnd; i++)
				{
				setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
				timer++;
			}
		}
	}
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
    var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
}