Ian McDiarmid was great in the prequels, but I wouldn't go so far as to say that he is a great actor. He has acted and sounded pretty much the same in everything I have seen him in.

I originally joined this board because I wanted to fan-edit Episode III. Back then I collected movies and TV-series with Ian McDiarmid just for collecting lines of him - and yes, all his characters' lines sound as if Palpatine delivered them.

BTW, there is also a lot of Liam Neeson's lines from other movies that you could reuse as lines for Qui-Gon Jinn. (Just add lightsabers to Batman Begins. :-þ ... ) Up to the point that he started channelling Charles Bronson, that is...