Guiliani and Clinton as 2008 presidential contenders?

In a recent poll both Rudy Giuliani and Hillary Clinton were leading their respective parties in the 2008 presidential race. Neither to me is a very strong candidate. Speaking just in historical terms, no sitting senator has won the presidency since JFK in 1960. For Giuliani, can an ex-mayor really win the presidency? No past president has ever won from such a low office (the closest I can think of is William H. Harrison, who was a war hero with no political experience). Anyone with a political background had come either from the Senate (for example: B. Harrison, Harding and JFK), Vice-presidency (Adams, Van Buren, Tyler, Fillmore, Arthur, T. Roosevelt, Taft, Coolidge, Truman, Johnson, Ford, and H. W. Bush), cabinet/minister (Jefferson, Madison, Monroe, Buchanan, and Hoover), or governor position (Hayes, McKinley, Clinton, and W. Bush). In recent years, its the governor position that will take one to the White House.

Knowing this am I the only one that thinks Haley Barbour and Mark Warner might be the darkhorse candidates? Both are southern governors who are moderate socially and conservative fiscally. In addition, Barbour and Warner have the added advantage of knowing that the last two presidents have been southern governors. The south is a rising political force, not only because of its increased population but also the Republican dominance and hispanic vote. It only makes sense to find a candidate (esp. for the Democrats) that is from the south. Bush already had one of the biggest states in the Union (Texas) for his presidential run in 2000. In 1980, Reagan started with the powerhouse state of California. Clinton, in 1992, had ... uhhh ... Arkansas? Well, that might be the exception that the doesn't disprove the rule. At any rate, don't count out a southern governors.