Configuration problems.

Hi All, I'm trying to set up PHP-4.0.2 on a server where someone else has installed Apache already. However, I keep getting the same error - can't find httpd.h - even though I've done a search of the server and tried to set the --with-apache=/directory/of/apache to just about every directory on the server. I can't actually even physically locate the file httpd.h (which seems odd). Does anyone know a way around this? I don't quite understand the difference between configuring it for Apache and making a CGI version. Any help would be greatly appreciated. Best regards, Andy