I wouldn't run Oracle or even PHP or Apache on win98. too unstable and poor performance. You might have better luck on NT. Linux of course would be much better.
I am running the following set-up:
Windows NT Server 4.0 SP 5
Apache/1.3.12
PHP 4.0.2
Oracle 8i NT version
Install Apache and PHP4. Get it working with some of the modules like zlib, pdf, odbc , etc. This config is done by editing the php.ini file that you place in your Win directory in NT, it would be: X:\Winnt
Install Oracle 8i and create a database. When done edit your php.ini file and add the following, to add oracle 8i support for older versions of oracle add the next one:
extension=php_oci8.dll
extension=php_oracle.dll
make sure you specifiy the correct path for the extensions:
ex. extension_dir = c:/php/extensions/
I also recommend running Php4 in CGI mode, as it is more stable but not as fast. edit you httpd.conf file of apache to read something like:
ScriptAlias /php4/ "C:/php/"
Action application/x-httpd-php4 "/php4/php.exe"
AddType application/x-httpd-php4 .php
AddType application/x-httpd-php4 .php4
AddType application/x-httpd-php4 .phtml
hope this helps.