"This tutorial shows how to install and use suPHP with PHP4 and
PHP5. suPHP is a tool for executing PHP scripts with the
permissions of their owners instead of the Apache user. With the
help of suPHP you can also have PHP4 and PHP5 installed at the same
time which I will describe at the end of this article.
"suPHP integrates into Apache2 as a module. At the time of this
writing it does work with Apache2 prior to version 2.2. Version 2.2
is not supported yet..."