Viggo Mortenson is Aragorn in The new Lord of the rings films.
I picked DeNiro because I think hes a good actor and could pull it off although I agree that Ventura is an equally good choice.
The guy from lock stock you suggested did actually cross my mind but I think hes a bit old personally.
EDIT: Cody you beat me to the reply with the Viggo question.
That was some speed! Did you smell a LOTR question?