$(document).ready(function(){
    var leftHeight = $('#contentLeft').height();
    var rightHeight = $('#contentRight').height();
    
    if (leftHeight > rightHeight){
        $('#contentRight').css({
            'height' : leftHeight +'px'
        });
    }else{
       $('#contentLeft').css({
            'height' : rightHeight +'px'
        }); 
    }
});