Poll: In 2008, most Americans want a Democrat elected

Lately when we see Democrats leading Republicans in polls, it usually has to do with this year's midterm elections.  But in the latest Newsweek Poll, most Americans want a Democrat, not a Republican, in the White House in 2008:

"Now thinking ahead to the next presidential election in November 2008: In general, would you rather see a Republican or a Democrat elected as our next president in 2008?"

Republican - 31%
Democrat - 50%
Other Party - 2%
Unsure - 17%

However, in almost every head-to-head match-up poll, John McCain beats every Democrat.  Interesting how these polls often contradict one another.