Drupal Dev Environments

FREE Drupal and PHP Dev Tools
On Sept. 15th, the Surrey Drupal meetup is having a panel discussion on Drupal Development Environments called How do you Drupal? So in preparation, I'm writing about the Dev environment I use everyday, (XAMPP 1.6.8 for Windows), ones I've tried out (Acquia Dev Desktop, Zend Studio) and one I plan to install soon (VirtualBox, QuickStart and Drush). What are your favourite Development platforms and tools? Leave your comments below.