Brand new server - PHP giving weird error

Ok, we’ve just installed a brand new server running Windows 2003 and IIS 6. I installed PHP 5 using the EXE automated installer thingo which does everything automagically. I went through and checked, and everything is done - ISAPI filter set up, scripts enabled, etc…

But whenever I try to access a PHP file from a browser, it just gives me a blank page with “No input file specified.”

Any ideas??