Well if u can use php you can redirect user by there browser language...
like this
PHP Code:
<?
if(strstr($HTTP_ACCEPT_LANGUAGE,"es")) {
echo"<script>location.href=('http://www.spanishsite.com');</script>";
}
?>
Else you can do the same thing by javascript.
look in google for "browser language redirect javascript"
or somthing... i'm sure yu will find something!
Browser rediect is not bulletproof tho!
everybody can use an english language browser...