Create a .php file that only contains
<?php
phpinfo();
?>
access that from a browser and see if php is configured with mysql support.
Your output from phpinfo should have a MySQL section, here is an example one yours should have similar mysql info http://74.125.47.132/search?q=cache:Pto_DJIncV8J:www.entropy.ch/software/MacOSX/php/test.php+phpinfo&cd=6&hl=en&ct=clnk&gl=us&client=firefox-a
In Windows that means that PHP couldn't load the correct DLL.
Fatal error: Call to undefined function mysql_connect() in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\mysqltest.php on line 2
In your PHPInfo, the extension_dir is set C:\php5 It seems that the php_mysql.dll is missing in that directory. Look for it in your installation and copy to c:\php5 or change your extension directory.
For more info you ought to check the manual
Hi, it is difficult to tell without the actual error. In you php.ini the extension=php_mysql.dll is set, so it may be ok. Check running as MindStalker said
phpinfo();
to see if the extension is loaded actually, and then check mysql connection
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
die('Could not connect: ' . mysql_error());
}else
echo 'Connected successfully';
mysql_close($link);