So if I understood you correctly you want future installations to go onto the new drive, right?
open regedit and navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
Locate the value named “ProgramFilesDir” in the right window, double click it and change the default value
“C:\Program Files” to your new directory path(address).
But whatever you do, make sure you read and understand this Article first:
Microsoft does not support changing the location of the Program Files folder by modifying the ProgramFilesDir registry value
Mind you, I have 32 bit so your default folder might have a slightly different name
In the long run it might be safer to give the new path during installation (usually called Custom Install)