Despite almost being on Robert Downey Jr. (Iron Man 2) and Zach Galifianakis (The Hangover) overload, I’m beginning to shed my initial reluctance to director Todd Phillips’ new comedy, Due Date. After the second full-length trailer and this new redband preview, I have to admit, this looks hilarious. Still, I think Due Date probably will fare better for Downey Jr. than it will for Galifianakis. Why? Look at Downey Jr.’s resume. The guy has talent and range; he can star …