Versions from 1.7.0 provide PHP 5.3, with which some of the Joomla extensions do not work. You need Joomla core 1.5.15 or newer.

Version 1.6.8 provides PHP 5.2.6.

The document root is usually located at C:\xampp\htdocs. I do not recommend to change this, but rather add an additional directory path with your development files to it. To do this, you need to set the apache config accordingly. To do this, modify file C:\xampp\apache\conf\httpd.conf as follows:

1. Below the <Directory “C:/xampp/htdocs”> directive, add a directory directive for your development files.
2. Find the <IfModule alias_module> directive where the aliases are defined, and add the following alias for apache to find the path: Alias /joomla D:\your working directory.