Well I tried to install PHP 5.5.9 and I followed the procedure in this video exactly: http://www.youtube.com/watch?v=6Y6lOHov3Bk
Basically I pasted these lines in the httpd.conf file, saved and restarted my computer.
# For PHP 5 do something like this:
LoadModule php5_module "c:/php/php5apache2_4.dll"
AddType application/x-httpd-php .php
# configure the path to php.ini
PHPIniDir "C:/php"
And now when I try to start Apache it does not work, and the last line in the error log is the following.
(Cannot start Apache (c:/php/php5apache2_4.dll into server: The specified module could not be found)
The only thing I can think is that when I downloaded the PHP 5.5.9 zip file and unpacked it, it did not have the php5apache2_4.dll file so I had to download it from a 3rd party website: http://download12.mediafire.com/9ory5zibr0zg/ncwlddm9cclwc99/php5apache2_4.dll