My recommendation.

Since CCK and Views is still in development on Drupal 6.x, I think we should get OSDPL working the way we want in Drupal 5.7 since all the modules we need are present and stable.

Do a test upgrade to 6.x once CCK + Views is available for that version. If everything looks good, then we can then do a real upgrade on the live site.

Upgrade guide can be found here:
http://drupal.org/upgrade/tutorial-introduction

Seems pretty straight forward. Hard to anticipate if anything will go wrong during the update.

Since we're running a pretty generic Drupal site, I hope that we won't run into problems.

backup and creating a test site will be necessary to ensure we do not have downtime during a migration.

iteration06