OK, here are some more things that I want to add about "Silence".
1) Original story. Currently I have only talked about Kichijiro, the peasant who betrays Rodrigo, but there is another key role - albeit smaller role than Kichijiro -, Inoue Chikugo-no-kami, "bugyo" (a function of a local government that combines police and court in Edo period). The "BAD guy" who persecute Rodrigo.
Well, in this novel, "bad guy" is not that simple a bad guy. This is another VERY complex role. Inoue used to be a Christian himself, and he must have gone through deep thoughts about converting. There are some important discussion scenes between Inoue and Rodrigo. He is the one that invented the REAL nasty torture, but in the novel, you don't get the impression that this guy is simply a heartless bad guy.
In 2-channel discussion board, someone suggested "Teruyuki Kagawa as Kichijiro" (as I did) and "Hiroyuki Sanada as Inoue", and I remembered that role. (I read this novel some 20 years ago, so I forgot some parts of it. I had to go to Wikipedia to remember some details.) I think this role is more suitable for Sanada-san.
2) Filming schedule. Some Japanese articles about Scorsese's announcement in Cannes says that he plans to do some filming in Japan in summer 2008. So it is a really long filming schedule - I am not sure when they actually start, but reiko, you are right, Sanada-san can well acommodate this schedule, even with "Speed Racer".