Mike, I agree that the Gallup poll you just cited has some good news for Hillary. But I think the subject of "change" really involves two separate questions. The Gallup poll got at one of them--whether people want specific policy changes (what Hillary, Obama, and Edwards are all selling) or broader systemic reform (what only Obama and Edwards are selling). That they seem more interested in the first bodes well for her--though Obama would say he doesn't favor reform for the sake of reform (or bipartisanship for the sake of bipartisanship), but as a more effective way of getting these changes enacted.
The other change-related question is a little more superficial but still important (maybe more so): Who do you want implementing those changes--someone new and exciting or someone old and familiar? I think this is where Obama enjoys a potential advantage. "New" can be a little scary and is almost by definition uncertain, while "old/familiar" can be comforting. But it also (again, almost by definition) carries a lot more baggage.
There are a lot of voters who, even if they trust Hillary to bring about health care reform and end the war, just don't feeling like spending four or eight more years with the personalities who defined the 90s. If Obama's going to win, he's going to have to draw those feelings to the surface more explicitly.