The GOP ran 13% ahead of its national numbers in North Carolina in the Presidential elections of 1996 and 2000. With Edwards on the Dem ticket, it might be asking a bit much to match that performance, but a differential of 8 to 10% seems to me to be doable, and that could be enough to pull Burr in -- maybe Ballantine, too, in the gubernatorial race. Especially if that 8 to 10% differential is on top of a national margin of a few percentage points in President Bush's favor.
Coattails are important. Remember Ronald Reagan pulling John East (let's face it, a weak candidate) through in 1980; remember G.H.W. Bush, even as he lost his re-election bid, pulling Lauch Faircloth (another weak candidate) through in 1992. No GOP Senate candidate in North Carolina has lost in a Presidential election year since 1968.
I think we could also add the mother of them all, the very popular Jim Hunt losing to Jesse Helms in the 1984 Reagan landslide. If Hunt couldn't do it, Bowles would have even less of a chance.