Converting Characters In A Variable To Individual Values In An Array turning variables into arrays

Say I have a variable such as $nav_item and it had to contents Home. IE:

 

$nav_item = 'Home';

How would I make so that $nav_item was an array and had the following contents?

 

$nav_item = array ('h', 'o', 'm', 'e');

With the case changing (ie H would become h and U would become u)

 

EDIT: Okay found out that I could change the case with array_change_key_case ($nav_item, CASE_LOWER);

Taken from http://us2.php.net/manual/en/function.preg-split.php

$str = 'string';$chars = preg_split('//', $str, -1, PREG_SPLIT_NO_EMPTY);

You can also just access individual characters in as string by treating it like an array, so "$str[2]" would return "r".

Thank you WindAndWater