Rudy vs. anybody shifts the swing states. Rudy's got a ton o appeal in strong Dem territory of the northeast U.S. He's got a lot of negatives for some of the true Republicans in the South and parts of the West.
I doubt too many of the strongest red or blue states switch, but I can certainly see New Jersey and Pennsylvania, maybe even Connecticut and Delaware coming into play for Giuliani. Depending on the Dem, NC, VA, Tenn, Ark, even Kentucky could be swinging... I wonder if Indiana could also become a swing state.
I think Rudy is much more of a plus in places like FL, PA and OH, than he is a minus in any Southern state. In a close election, I can't see Rudy losing any Southern state unless the state is a home state for the Dem ticket.