can Apache be used as a proxy server on a windows server 2008 machine? Does it also require PHP to be installed?
Yes, Apache can be used as a proxy server on Windows, using the built-in mod_proxy. PHP is not required for the proxy functionality. We have been using it as a reverse proxy for years running on Windows Server 2003 with no issues, and there is no reason why Windows Server 2008 will be any different.
I recommend you use the latest stable 2.2 version as older versions had some issues with the reverse proxy functionality.