aegirr on "Error establishing a database connection"

I still cannot install WordPress locally. Here is more informastion about the situation.

I am using Windows 7. I can see in the XAAMP Control Panel that the web server and the database is running. The Control Panel tells med that the database is using the port number 3306, but this line in wp-config.php does not work:

define('DB_HOST', '127.0.0.1:3306');

What is stopping WordPress from contacting the database? Any ideas?