What changes are needed if I change directory structure? I can't have a mess of craft stuff at the root of my server so I try to use the following directory structure, with craft files and folders gathered in a craft directory :

craft
-- config
-- modules
-- storage
-- vendor
-- etc...
www
-- index.php
-- web.config
-- etc.


This structure gives me a 500 error.
I assume I can change a path variable somewhere, but I just can't find where. Any ideas ?
You have to define the path to Craft in your www/index.php file.

define('CRAFT_BASE_PATH', __DIR__ . '/../craft/' ); // &lt;- in your case something like this


The constant CRAFT_BASE_PATH must point to your /craft folder