I have Apache and PHP installed on my machine. I have a couple of test files in C:\Archivos de programa\Apache Software Foundation\Apache2.2\htdocs, and they open fine in Firefox. However, when I have the file open in Rapid PHP and click on "Preview", I get a message to say that the software is not yet configured. I've tried configuring it every which way, but nothing works!

I do find some of the instructions a bit ambiguous, but I've tried all the alternatives I can think of, without success. Doubts I have are things like:
should there be a trailing slash on the path names?
should the path to php-cgi.exe include the filename or just the folder?
At the moment, the document path is specified in Apache's httpd.conf without the slash, but I've tried it with as well.
I see that the Built-In Web Server settings include a port number that defaults to 89. I haven't tried changing it, but is that right?
Any help or advise gratefully received.