There is a possibility Romney or Giuliani might lose New Mexico (5 electoral votes) since it has been teetering on the fence between Dem and Republican. Gore won New Mexico in 2000 and Bush won it in 2004 but by only 0.8% over Kerry in the popular vote. I see a good chance for Rudy or Mitt to win Michigan in 2008 (17 electoral votes) for a net gain of 12 electoral votes. Mitt has a good chance in Michigan, his native state, and where his father, George Romney, was a very popular Governor elected three times and is still remembered fondly.
I do not know whether a conventional Republican or metro Republican such as Guiliani/Romney would best win and hold the Western states teetering blue (NM, NV and CO). I do not think that a Guiliani/Romney would be at any particular disadvantage.