Having trouble setting cookie in wordress: hit counter

Hi, hope someone can help.
I have a small amount of php code in my theme to output a hit counter. My client wants this feature. The counter only increases on unique users and this is maintained by saving a cookie.
The php code works fine if is saved to a separate php file (modified) and accessed directly but it just wont allow me to set a cookie from within wordpress.

My existing code:

$file = (TEMPLATEPATH."/count.txt");
$count_unique = 1;
$cn = 'gcc';
$count = intval(trim(file_get_contents($file)));
if ($count_unique == 0 || !isset($_COOKIE[$cn])) {
++$count;
file_put_contents($file, $count);
setcookie($cn, '1', time()+3600, '/','.localhost');
}
echo $count;

The domain in setcookie is localhost because I’m building locally.

Any help on this would be greatly appreciated, whether it be on the code or on a hit counter plugin (that works for unique visits).

Thank you in advance.