That's doable, however, if you do not want to reformat drive "D:", you'll probably run into problems as it most certainly was formatted using NTFS, then by default Ubuntu will not write to that drive. It is not safe to turn on the write feature on NTFS from Linux because all the information about the disk format is not known by the developers of the NTFS system under Linux.
If you have enough room on C: to copy all the data on D:, then you could:
- copy the data from D: to C:
- boot under Linux from a CD
- format D: using xfs4 or similar
- copy the data from C: back to "D:" (now under Linux it is a mount point such as /data)
If C: is too small to copy D:, then the best would probably to buy another hard drive and format that one with xfs4, copy D: to it, then install Linux on "C:" and you should then have all the data readily available. Once that is the case, you could format "D:" and use it too for backups or something.
Now, to share the files with other MS-Windows boxes, you want to install Samba. That's enough and it does not require you to have a disk formatted with NTFS. Samba is relatively simple if you do not need super high level of security. Just make sure the Linux firewall is not in the way. You should search references and such about Samba so find out how to get it working.
D:
drive when installing Linux... – Alexis Wilke Oct 13 '14 at 11:39