[quote name='epobirs']The novelization and graphic novels suggest that C3PO had his memory wiped but not R2D2. This is kind of a nasty joke since only Threepio can really understand R2D2's 'speech.' It also explains why R2D2 is much more confident in the task set to him by Leia while Threepiois clueless. One wonders if R2D2 knew who Leia was in relation to his former owner all along.
Having the little pipsqueak as the only non-Jedi who knows what really happened through is pretty amusing.
Obi won never claims not to recognize the droids because the question never arises. He merely says he never owned any droids, which is entirely honest. Presumably the one that traveled with him in Episode II was property of the Jedi council rather than his own. The council appears much like the Catholic Church hierarchy in regard to property. This would also serve to explain the celibacy among the Jedi but that could also be chalked up to fears of the Jedi forming a closed breeding group within their respective species and creating a clan that rules the galaxy by default with their inherent strength in the Force.[/QUOTE]
After further research, I've seen that you are right about the droid memories... although I can't say how you're right... but you are

[quote name='javeryh']I just watched RotJ over the weekend and the scenes with Luke and Vader take on a whole new meaning knowing what we know now about how Vader came to be... one thing I don't understand though is why didn't the Emperor realize what Vader was about to do (throw him over the balcony) and why couldn't he stop him since he is so bad ass. It also makes me wonder why the lightsaber fights in IV, V and VI are so lame (other than having the money to hire choreographers) compared to I and II...[/QUOTE]
The Emperor thought (as well as Vader himself) that Vader's conversion to the dark side was complete. For all the Emperor's insight, he's not infallible - he can still be tricked. He always said that he can foresee the future but Yoda made it abundantly clear that, according to the Force, the distant future is always in motion and therefore not truly predictable. The Emperor thought Vader was fully in his thrall and incapable of such things. Plus, even if he knew, the Emperor has become an old man whose body is ravaged by the dark side of the Force. The dark side requires a huge price to use for the body so premature aging is a result of this. The Emperor wasn't young to begin with in the new trilogy and 20 yrs have past since then in the old trilogy so he was very very old by ROTJ. The only thing keeping him alive was his sheer will and drive in the dark side of the Force.