I have not seen Cinderella Man..but hope to.
Walk the Line - wanted to like it, but did not. I think that Joaquin's performance was wickedly accurate - the mannerisms, the prersonality probably (I really did not know Cash personally) but I found perky Reese annoying and definitely underserving of any award. I have spoken to people who do remember her (from concerts) and the real June Carter was nothing like reese's portrayal.
OTOH Joaquin captured Cash's spirit especially in the scene at Folsom...although if you've seen the real documentary at folsom you will understand that it's only a representation of the real thing.
In order to stay sane, I close my eyes and pretend that Reese Witherspoon won an Oscar for Election instead.