Código:
<html>
<style>
#celda{
width:200px;
}
</style>
<body onload="iniciarTabla();">
<table id="acusados" border="1" ystyle="border: solid 1px #7f94aa; text-align: center;" cellspacing="0" >
<tr>
<th id="celda" ><div>Nombre</div> </th>
<th id="celda" ><div>Primer Apellido</div> </th>
<th id="celda" ><div>Segundo Apellido</div> </th>
<th id="celda" ><div>CI</div> </th>
</tr>
<tr>
<td id="celda" ><div>Manuel</div> </td>
<td id="celda" ><div>Delgado</div> </td>
<td id="celda" ><div>Fernandez</div> </td>
<td id="celda" ><div>87112734953</div> </td>
</tr>
<tr>
<td id="celda" ><div>Pedro</div> </td>
<td id="celda" ><div>Hernandez</div> </td>
<td id="celda" ><div>Lopez</div> </td>
<td id="celda" ><div>87112734954</div> </td>
</tr>
<tr>
<td id="celda" ><div>julio</div> </td>
<td id="celda" ><div>Frenandez</div> </td>
<td id="celda" ><div>Figueredo</div> </td>
<td id="celda" ><div>8711273495aaaaaaaaaaaaaaa<br />aaazaaaaaaaaaaaaa5</div> </td>
</tr>
</table>
<script type="text/javascript">
function iniciarTabla()
{
var tabla = document.getElementById('acusados');
filas = tabla.getElementsByTagName('tr');
var cont= 0;
for (i=1; i< tabla.rows.length; i++)
{
tabla.rows[i].cells[0].onclick = function() {crearInput(this)};
tabla.rows[i].cells[1].onclick = function() {crearInput(this)};
tabla.rows[i].cells[2].onclick = function() {crearInput(this)};
tabla.rows[i].cells[3].onclick = function() {crearInput(this)};
nueva_columna = tabla.rows[i].insertCell(4);
ele = document.createElement('input');
ele.type = 'button';
ele.id="celda";
ele.value = "Eliminar";
ele.onclick = function() {borrar_acusados(this)} ;
nueva_columna.id = 'celda';
nueva_columna.width='20px';
nueva_columna.align='center';
nueva_columna.appendChild(ele);
}
}
function borrar_acusados(obj)
{
tabla = obj.parentNode.parentNode.parentNode;
tabla.removeChild(obj.parentNode.parentNode);
}
function getDiv(obj){
divs = obj.getElementsByTagName('div')
return divs[0]
}
function crearInput(celda)
{
celda.onclick = function() {return false}
ancho = getDiv(celda).offsetWidth;
txt = celda.innerHTML;
celda.innerHTML = '';
var textbox= document.createElement('input');
obj = celda.appendChild(textbox);
obj.style.width = ancho+'px';
obj.value = txt;
obj.focus();
obj.onblur = function()
{
txt = this.value;
if(!validarLetras(txt))
{
alert("Error: verifique que el campo contenga solo letras");
}
celda.removeChild(obj);
celda.innerHTML = txt;
celda.onclick = function() {crearInput(celda)}
}
}
</script>
</body>
</html>
Eso te soluciona el problema de el tamaño....