|You are allowed a total of 4 primary partitions or 3 primary partitions and one extended partition which can have a number of logical drives on it. Your D drive is your recovery partition and counts as one, your main boot partition is one more, but that is only 2. Your boot partition MAY be counted, but I do not think so, unless you have others you did not mention.|
One option might be to get a new larger drive, back up your files, make a recovery DVD, clone the drive onto the new one except without the recovery partition or restore from the recovery DVD to the new drive, and partition that one instead (saving the original drive for emergencies).
You have to be a little bit crazy to keep you from going insane.