I assume you have already found a solution. But here is the solution that I have written and am currently using, which is very flexible and easy to use: http://sl4dragdrop.codeplex.com/
It works very well on SL5, all you have to do is add the dependency properties of the elements or controls on which you want to enable drag and drop.
By default, this is enough. But if you want to customize the parts of the drag and drop, this gives you interfaces for implementation that can control things like the Drop item, Which item to drag, What image to show when dragging, etc.
I recently refined it a bit and will soon post an update after some testing.
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