This is a major argument now among us star wars geeks. I would say for the full experience, you have to watch it starting with Episode I, Phantom menace, then clones, then sith, then go to the OT. New Hope, Empire and Jedi. If you have not watched the originals yet, this will be a great way to see the story from beginning to end. Watching the original str wars, ANH, after having seen Sith puts everything in a whole new light.