Unfortunately PHP5 removed built-in support for mySQL. So you´ll need to copy some files by hand. open the folder you unzipped your PHP to. Copy the libmysql.dll file (should be located like C:\Server\php\libmysql.dll ) into your Window´s System folder (usually C:\Windows\System32\ although might be c:\WinNT\System\ or something).

Then open up your php.ini in a text editor and search for ;extension=php_mysql.dll and remove the ; in front of that line.

Do the same for ;extension=php_mbstring.dll. Without the mbstring extension phpMyAdmin is unable to split strings correctly and it may result in unexpected results.
Restart Apache and see if you get any errors. If it complains about php_mysql.dll either your extention directory isn´t correct or windows can´t find libmysql.dll

If you don´t want to move files outside your php5 directory, you may also add the php5 directory to the PATH on Windows.

Now you are done.

Getting PHP5 to work with mySQL, mySQL, PHP5