setting up FastCGI on IIS (SBS2003 version) - simple PHP scripts produce errors

I want to get PHP scripts working thru' our IIS webserver on SBS2003 (which is IIS 6.0 I believe - though this from hearsay, as the MMC interface to IIS doens't seem to give any version info for IIS)

I installed PHP and got simple scripts working from the command line (strewth!).

I installed FastCGI from
http://learn.iis.net/page.aspx/247/using-fastcgi-to-host-php-applications-on-iis-60/
and followed all the steps

When I tried to surf to the following noddy PHP script:

<?php
    echo("A simple but effective PHP test!");
?>

My browser (IE) returned the following:

FastCGI Error
The FastCGI Handler was unable to process the request.
--------------------------------------------------------------------------------
Error Details:
The FastCGI process exited unexpectedly
Error Number: -1073741819 (0xc0000005).
Error Description: Unknown Error
HTTP Error 500 - Server Error.
Internet Information Services (IIS)

I am able to browse to simple *.htm pages in the same folder, just not able to run any *.php !

any ideas, or further info, pls don't hesitate