Sysem/Users/Libraries on wrong (smaller) drive

Okay, so my wife bought a laptop from a friend. It's got 2 drives "c" with the OS and "d" with vast amounts of empty space. Problem is, all the users and libraries (and all those files) are sitting on "c". Seems like the system should be on D but all the libraries on C with all that space. It's a Dell Studio and I do remember partitioned drives on Dells but I'm new to Win7 and lost.

Any pointers?

Thanks-
Rich