downgrade drupal 7 to drupal 6 I need to downgrade Drupal 7 installation to Drupal 6, how should I handle it? I have pretty much blank Drupal 7 install (w/ bunch of users, which I really don't want to loose), but the module that I need only works on Drupal 6.

* UPDATE *

following is a module that I'd like to use w/ Drupal: Clickbank IPN | drupal.org and as you see developer(s) don't have anything other then d6 release.

Is there a way to export users from D7 and import then to D6?
You wont be able to find any easy solution to downgrade from 7 to 6. The best option is to either find an alternative to the module that is not available for D7 or check the issue queue of that module you might find the dev release of the module. OR If only users are important to you then just export the users from D7 and import them on D6.