I was trying to work with a Drupal under XAMPP and while installing Drupal 6.13 I ran into file permissions on my XP box. It took me a while to find the solution to change file permissions so I thought I might help some other out and post the links that helped me out.
1. http://drupal.org/node/202491 Modifying Windows file permissions
2.http://www.ekhoury.com/2007/01/15/permi ... hp-on-iis/
Make sure you only change permissions on the files that you need. You will also need to be logged in as admin under XP in order to do this.
Hope this helps.