function disableEnableField(selectBox, fieldToDisable)
{
    var disable=false;

    if(selectBox!=undefined)
    {
        //if(document.getElementById(selectBox).selectedIndex==0)
        if(selectBox.selectedIndex==0)
        {
            disable=true;
        }
    }

    if(fieldToDisable!=undefined)
    {
        var boxes = document.getElementsByName(fieldToDisable);
        if(boxes!=undefined)
        {
            for(var i=0; i<boxes.length; i++)
            {
                boxes[i].disabled=disable;
            }
        }
    }
}