I have Apache 2.2.3 running fine, but I can't seem to get PHP 5.16 working at all on it. I did restart after modifying the httpd.conf file. I followed the directions given on the PHP website. Could I be editting the wrong httpd.conf file? Because there are Apache folders in my /etc directory.

Assuming you configured apache with the --enable-so option (enable modules), and php with the --with-apxs2=<apxs2 path> (use apache), you should find the correct config file in the same directory that apache is installed.
On mine it's /usr/local/apache2/conf/httpd.conf -- make sure the module is enabled, and that you add the file associations correctly.
Then kill apache, and restart it.. make sure to restart the correct one (give the full path to the binary) - I've been caught out by that before.
Slackware installs Apache 1.3.3 by default I think.. in the end I removed the package for that.

I didn't add those extra things while installing. When I get the chance I'll have to recompile with those. They never crossed my mind, thanks for the help. And hopefully that'll work for me.