2008 is going to be a strange election year. In the last several elections, we've never had as many viable candidates (Clinton, Obama, Edwards, maybe Richardson; Giuliani, McCain, Romney, maybe Huckabee, surely Ron Paul can't win, can he?). In the recent past, each party has had either one or two strong candidates
2004 (Bush; Kerry, Edwards)
2000 (Bush, McCain; Gore, Bill Bradley--remember him?)
1996 (Clinton; Dole, Pat Buchanan)
1992 (Bush; Clinton, Tsongas; Perot)
Anyway, the trend has been to compress the schedule of primaries, because with only a couple of strong candidates, everything would get settled after Iowa and New Hampshire. States keep moving their primaries earlier in the year.
This year may be different. If three strong candidates remain after Iowa and New Hampshire, it may well be that they divide the various states on February 5 too, because no one will have momentum. That would be very odd, and it may well be that the later states (Ohio, Rhode Island, Texas, Vermont on March 4) will cast the deciding votes.