PHPRC Cacti and X-Cart

[bobsonbemoi]

I have set up X-cart on my IIS 6 (win 2k3). All is well until I try to set up Cacti. I would like to graph a few things like traffic load and stuff like that, that's why I need Cacti. Cacti requires two environment variables: MIBDIRS and PHPRC. When i set PHPRC to the directory (or any other for that matter) where PHP is installed, my whole web server stops understanding PHP altogether: neither X-cart nor any other application requiring PHP works. It just says 404 not found (or may be 40? something). Why the hell does IIS stop understanding PHP scripts when I set the PHPRC variable.