I would prefer the first one Arlie. The wizard would be nice at first, but I think eventually the grid option would be better to make little tweaks.
As an aside, I think instead of a grid, a different gui design choice could be sliders, with the other sliders in a column auto-adjusting themselves to sum up to 100. There would have to be a way to 'lock' already set sliders in place so they don't get changed if the user has already set the desired % for that category. Just an idea.