Upgrading From 5.x-2.x -> 6.x-2.x

1) If FileField is not already installed, disable ImageField.
2) Upgrade Drupal and contributed Modules to 6.x.
3) Run Update.php 
4) If FileField is not already installed
  a) install FileField 
  b) enable both ImageField and FileField.
  c) run update.php.