I've found cross-overs to be about even, slightly leaning Bush, but almost deadheat. (More Gore voters voting for Bush than Bush voters voting for Gore), About 54-46 in Bush's favor, but it varied from state to state (higher in New York, New Jersey, California[arnie effect]).
There are also a decent number of "dormant" voters. People who've voted in the past, but neither in 1996 or 2000, that will be voting for Bush. There is a clear lean towards Bush in this category, around 60-40.
New registers are breaking about even.. varying from state to state.