To add space to the c-drive, the freespace would have to be right next to the partition you're wanting/needing to expand. So If D: starts right where C: ends, you cannot expand, unless you were to delete the D-partition.

Yes - I was planning on doing a back-up to tape and to external usb of D and E. Then deleting D and E within windows disk manager Running extpart on c to make it bigger Then re-build D and E and copy the data back to them