Reports ‘missing the MySQL’

Hello All

I use IIS 6.0, Windows XP SP2, PHP 5.0.5 and MySQL 5.0.18. My information:

Host: localhost
User: root
Pass: 123
Database: wp

I can connect my MySQL database with the following command in the command prompt:

mysql -uroot -p123 -hlocalhost -Dwp

I have changed the wp-config.php as following:
define(‘DB_NAME’, ‘wp’);
define(‘DB_USER’, ‘root’);
define(‘DB_PASSWORD’, ‘123’);
define(‘DB_HOST’, ‘localhost’);

But whenever I run http://localhost/wordpress/wp-admin/install.php it says: Your PHP installation appears to be missing the MySQL which is required for WordPress.

What can I do? However, I have already created the database named ‘wp’. Thanks in advance.