Originally Posted by Capt. Picard
I can't remember what I did 2 years ago when I last installed 2 OS's on a PC.
Which OS should I install first?
Windows first, ALWAYS. Anyway when you install any Linux-based OS, the GRUB bootloader is the one to take over the bootloading process, so the usual partition order is:
(or if you tend to customize the ubuntu-derivative installation)