I thought Samuel L Jackson's dialogue was a little hard to believe, it just seemed like he wa acting not really the character in any way.
Christopher Lee was Awesome in the movie acting wise. But you are right, he needed something he could better sink his teeth into, though he pulled off an amazing job.
Security Guard only may have had a few lines but they were horrific.
Jango Fett was a pretty good actor, and compared to the kid who played Anakin last go around Boba was a god.
I don't think Natalie Portman's acting was that bad, actualy thought it was allright, she was in between: Never really horrible and as far as I could see never really good. But you're right, she was givin such a cut - out role in both movies though Episode 1 was the worst. But she is in my opinion the second most beautiful woman alive and that skin tight white outfit almost made me faint!
And Mcgregor was really really good, he doesn't get enough credtit as an actor. Hes been good in all the movies I;ve seen him in. I really liked him in Moulin Rouge actually, so sing his praises.