I've done a fresh re-install of php from those instructions; now getting an error 500 for php files.
I've checked that iusr has the relevant permissions to read & execute, but it doesnt like it... any ideas?
I'm able to process the .php files on the command line using both php.exe and php-cgi.exe - it does output sensible code... the problem seems to be in that being redirected through IIS to the outside world...