function opacity( id, opacStart, opacEnd, millisec ) {
    //speed for each frame
    var speed = Math.round( millisec / 100 );
    var timer = 0;

    //determine the direction for the blending, if start and end are the same nothing happens
    if( opacStart > opacEnd ) {
        for( i = opacStart; i >= opacEnd; i-- ) {
            setTimeout( "changeOpac(" + i + ",'" + id + "')",( timer * speed ) );
            timer++;
        }
    } else if( opacStart < opacEnd ) {
        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 + ")";
}