GetUsers( $Server, $UserPrefix, < $List | \@List | \%List > )
    This will, if successful, populate the @List array with the names of the 
    user accounts which begin with $UserPrefix.
    $UserPrefix can be an empty string in which all user accounts will be returned.  This parameter is
    case insensitive.
    $Server is either:
      - The name of the machine the accounts reside on in either "\\\server" or "//server" format.
      - The name of a domain as in "Accounting" where the user accounts reside.
      - An empty string ("") which returns the user accounts for the local machine.

    The third parameter can either be a scalar, an array reference or a hash reference. If it
    is an array then upon success the group names populate the array.  If it is a scalar then 
    it is converted into a hash reference.  Hash references are populated with the user id, full
    name, comment, and account flags.

    Returns:
        The number of group names stored in the array or hash.