Defarge has a great point, it it was him, would he have a chance of winning some new england states?
In the general election? He would win NH and quite possibly NY. Other New England States will probably be reliably Democratic.
The Primaries will be a completely different story should Giuliani decide to run. I'm not a Republican, and don't pretend to know the internal workings of their party, but this is what I would guess. Giuliani gets completely crushed in Iowa, 3rd, 2nd if he's extremely lucky. Next week, Guiliani wins NH. In the procession of primaries and caucuses in between NH and Super Tuesday, Giuliani will lose most, if not all of them except for North East, West Coast, and some Midwest Primaries.
At that point, it's just a question of whether Giuliani can hold out until Super Tuesday, when he wins the blue state Republican primaries, including NY, CA and the rest of the North East. If he can translate those victories into momentum, he could win the nomination.
However, it's a long shot, and depends on Red State primary voters listening to their Blue State Republican counterparts. In addition, there's the simple fact that there are 3 more years until the Iowa Caucuses. Anything can happen. Anything will happen.