Yep, like tha_mink says, the server needs to be configured to treat .php files as PHP code (using the browser to "View Source" would have made it obvious what the problem was).
These lines need to be in your httpd.conf
AddType application/x-httpd-php .php
and
LoadModule php4_module libexec/libphp4.so
If they are there (and they're not commented out) then one thing that may work is to replace <? with <?php in the PHP files (and <?= with <?php echo if such things are there) - I'm reluctant to suggest turning "short tags" on.