Yes, you can install Ubuntu on your "D" drive. I ran that way since February.
First download 14.04 and install it on a USB drive instead of a DVD.
What I did was remove the Windows HDD and then install Ubuntu with only the Ubuntu drive in the computer.
Then I added the Windows drive back. I had to set the BIOS to do the dual booting for me. Leave the BIOS in EUFI secure mode when you install Ubuntu.
The trick is when you leave Windows to boot to Ubuntu. You'll need to do a complete shut-down. The shut-down in Windows normally is just a hybrid of hibernate and sleep. You'll need to hold the shift key down while clicking the shut-down option in the menu.
Since I mostly used Ubuntu, I set the BIOS to boot to the Ubuntu drive as the primary.
When I was ready to boot Windows, when the computer gave me the option of going to the BIOS or boot menu, I pressed F-10 and it gave me a choice of windows or ubuntu. I chose windows and operated. When leaving Windows, I had to do a full shutdown or start a reboot in order to get the boot option menu again.