Ditto that. But, it won't be Allen. More than likely, the major candidates in the end will be Sanford, Owens, Romney. Wildcards are Gingrich and Giuliani. Veep candidates will include Pence, Rice, and any of the closest contenders who don't get the nomination.
The first 2 people you named, are committed and on record as NOT running for president in 2008.
Romney is running, but will probably be out of the elections by super tuesday.
Gingrich is a wild card, but probably not going to run and will use election talk to push his book (great book by the way).
Rudy will not placer higher then 3rd in New Hampshire, and will be finished by South Carolina.
Mike Pence would never, ever take a VP slot, and Rice is already ruling it out.
George Allen, if he gets right endorsements, will probably wind up with the nomination, his good luck might be that he faces a really weak democrat in the general election, if he is lucky, it will be Hillary Clinton.