What do you mean by Partition the Other half and not losing anything?.
Do you mean Format and not hurting your installations or You Think you still
have Data on it and would like to keep?.
Since you performed a clean install and created a New Partitions you lost
old data if you didn't backup, If you are worry about damaging your new
installation that not true, nothing will be happen to your installation (i.e
the other partitions C:\).
Just Right click the D:\ Partition and click format and do a complete format
on it to use it.
Hope I got it right.
Let us know.
Regards,
nass