Hmm, I'm not too good at Apache on Windows. Come to think of it, not good at IIS, either. I guess for starters you'd make sure that you're writing to correct httpd.conf file, but I doubt that you've got more than one by accident (can happen on various 'Nixes).
If you have the AddType directive configured as above, it should work. Make sure the AddType directive is in a code block that's getting evaluated (for example, if it's in an IF block that's not applicable to your Apache setup.)
In 'Nix, you can issue
$apachectl configtest
and see if all's right in the httpd.conf file. Then try a restart.
Then, you've probably seen this...
http://us2.php.net/manual/en/faq.installation.php#faq.installation.phpandiis
However, I have to assume you've tried all this, so I'm rather at my wit's end too.
My apache on FBSD will even parse *.asp as php --- but I just did that to be mean, heh.