Installing apache2 and php5 on linux

first if there is any of these already exist in your system disable them (or make your life easy and use them). there is a great site describe this step by step.

http://dan.drydog.com/apache2php.html

if you are using Fedora (I use FC6) after installing https you should disable SELinux feature. Otherwise when you try to run httpd it will give you an error.
When giving the options to "./configure" in both httpd and php, give the ones you only need. Giving etra optins will not harm you but might have to do more edditing on config files. I recomend just configureing the opting you are going to use.
When compiling source (if you are like me) rather than installing from a rpm, its good practice to compile not as root. For security reasons and for the sake of simplisity.