Well, I have never seen or heard the scream before, but if it's true that's fine. I just don't see the reason why he changed it twice in the Special Edition and in the 2004 Edition. And I agree, it does sound pretty much like the Emperor's scream in ROTJ.

Anyway, but I just think that we probably have to expect a "Special Edition" of the Prequel Trilogy as well. Maybe when the 3-D Versions come out. Who knows. It's no wonder Star Wars is one of the most successful films. Look how many times he re-released it and everytime it brought him money.

SE-Trailer on the '97 VHS: "Now sit back to enjoy George Lucas' DEFINITIVE version of the Star Wars Trilogy"... Muhahahahaha