Forum Moderators: bakedjake
Is your current Apache installation compiled with PHP support in the executable, or do you use the CGI implementation or DSO (shared object) implementation?
If it's the first, then you'll need to recompile the Apache executable to support the new PHP version.
In the DSO implementation, you'll need to build a shared object for PHP5 (probably accomplished during installation of PHP5), and include reference to it in your httpd.conf file, replacing or complementing the PHP4 .so file, and then update your shared object library index to make it aware of the new object.
Note, too, that PHP makes no bones about PHP5 and Apache2 being uncomfortable together. You might want to go back to PHP4 until the bugs get ironed out.