Hi,
The only thing that needs to point anywhere is the php_oci.dll and php_oracle.dll, which are usually in the extensions directory and as you have enabled them in php.ini it should be okay.
After enabling does your webserver restart without any errors?
Your tnsnames.ora file (installed as part of the Oracle client) must have an entry to point to an Oracle database. Do you have access to an Oracle database either locally or remote?
Check the Oracle client is installed properly by running SQLPlus (usually found Start|Oracle|SQLPlus or something like that). Use your username, password and database name (as defined in the tnsnames.ora)
Mike