#conteudo {
 height: 300px;
 width: 610px;
}

#div1 {
 height: 300px;
 width: 300px;
 float: left;
 left: 5px;
}

#div2 {
 height: 300px;
 width: 300px;
 float:right;
 right: 5px;
}