The Democratic and Republican parties of today have almost nothing in common with the Democratic and Republican parties of 150 years ago. What does Barack Obama have in common with J.C. Calhoun, and what did Ronald Reagan have in common with John Brown?
The fact that the Democratic party was once the party of the Confederacy is about as relevant to today's political discussion as the fact that the Democratic party of the 19th century, from Thomas Jefferson to Grover Cleveland, was the party of states' rights and anti-Federalism.
I’ve answered this in my first post.