I would vote with the above user about pushing your personal files to the other drive.
Those tend to take a lot of space.
Now if that is not enough, you can actually move large programs(not ones that are a part of windows) to the other drive and create a junction to those old locations.
This in effect, makes windows see the programs as still on c : (this makes it so you do no need to install it over again) while they are in fact on d:.
The potential problem would be if the program has special NTFS security requirements(I have no seem many that do, but it can happen).
If a file does, robocopy /copyall would allow a direct copy with all permissions in tact.http://en.wikipedia.org/wiki/Robocopy
(GIU, but a bit strange. it says its done, but is still doing its thing. I recommend you make a script to run instead)http://en.wikipedia.org/wiki/NTFS_symbolic_link
(GIU, please use with care.)
Clone the old drive to the new one. It may be a faster drive. then use the old drive for files.