I have Windows XP and recently I installed wamp (apache-mysql-php) 32-bit. I tested the installation (connect to mysql database with php and apache) and everything was worki
When downloading the instantclient, verify that architecture have installed wamp.
In my case instantclient to download the x64 but had installed the x32 and had problems.
Downloaded the correct architecture and it worked fine.
[SOLVED]
I downloaded the Instant Client Package - Basic (version 10.2.0.5) and I extracted it.
Afterwards I copied all the files of that package in the following folders:
C:/wamp/bin/php/php5.4.16/ext/
C:/wamp/bin/apache/Apache2.4.4/bin
It worked for me in this way. After that the oci8 module was loaded.