Hi,
You can get more complete information here :
http://www.php.net/manual/en/install...extensions.php
For the installation of MySQL, I did the following modifications in the PHP.INI file :
extension_dir = "./ext/"
extension=php_mysqli.dll
extension=php_mysql.dll
Note that the lines are uncommented (i.e. without the leading ';').
Then, I created a folder 'ext' in the PHP directory, and put there the files 'php_mysqli.dll' and 'php_mysql.dll'.
I also copied the 'libmysql.dll' file into the folder C:\WINNT\System32 (because windows is there, could be C:\WINDOWS or anything else).
I found these files into the manual distribution of PHP.
The path to the PHP directory was specified during the installation of PHP, by adding it to the PATH environment variable (configuration panel / system / advanced).
Then, I restarted the machine, but I think you could jut restart the web server.
Then the install.php worked.
I hope this will be helpfull.