If Frank Darabont really does get to make "Doc Savage" with production partner Chuck Russell and Arnold Schwarzeneggar as Savage, there are five key roles (Doc's aides) to cast. Who will Darabont pick? There are two intriguing possibilities. One's William Sadler (who's in both Darabont prison dramas, "The Shawshank Redeption" and "The Green Mile") as either Long Tom Roberts, the spindly electrical wiz, or Ham Brooks, the dapper lawyer. The other? Michael Clarke Duncan, Darabont's Oscar nominee for "The Green Mile," as either Renny Renwick, the engineer with the really big hands, or Monk Mayfair, the giant-sized chemist who's Doc's main man.