Modifiqué tu código... fijate si algo así te sirve....
Código:
<html>
<head><title>Expresiones regulares</title>
<script type="text/javascript">
var letras = /^([a-z]|[A-Z]|á|é|í|ó|ú|ñ|ü|\.|-|\n)+$/
var car=" ";
function contar(){
var output = "";
input = frm.texto.value;
for (var i = 0; i < input.length; i++) {
if ((input.charCodeAt(i) == 13) && (input.charCodeAt(i + 1) == 10)) {
i++;
output += " ";
}
else {
output += input.charAt(i);
}
}
var count=0;
subtxt = output.split(car);
for(j=0; j<subtxt.length; j++){
if (letras.test(subtxt[j]))
count++;
}
frm.total.value = count;
}
</script>
</head>
<body>
<form id="frm">
<textarea id="texto" style="width: 500px; height: 150px;"></textarea><br>
<input type="button" value="Contar" onclick="contar()">
<input type="text" name="total" readonly>
</form>
</body>
</html>
<hr noshade size=1><img src="http://www.gograph.com/Images-8712/ClipArt/cat03.gif" height="50" border=0 align="absmiddle"> <font size="2" face="verdana" color="#000000">
bet[/CODE]