Hello Danzig, easiest way to do it would be for you to move some of your data from c: to d:
You cant physical move free space between drives but you can move the data.
Create a folder on D:\ and start moving your data etc etc over to it.
My system has two drives, a very fast 40gb hard drive for windows and apps, the second drive is a huge 200gb drive where I keep all my music, games and movies.
Hope this helps