Upgrade Drupal 6 to 7 using Drush 5 in Windows Drush 4 has a site-upgrade command for major version upgrades.

Looking at Drush documentation pages, and it looks like the command is not a feature in Drush 5. Is there a replacement or was it removed? I'm using the windows version of drush 5.
That functionality is now available as a separate module: Drush Site Upgrade


  The new home for site-upgrade drush command, which streamlines the major version upgrade process for Drupal.


There's also some reassurance that this will work with the latest version of Drush:


  IMPORTANT: Drush Sup 7.x-2.x requires Drush 5 or later.