Fortunately as luck would have it my boot order is the same as you describe, minus of course Ubuntu. That page about multi-booting although outdated, still had a lot of information that was useful, if not applicable to my situation, due to upgrades of Linux and Grub. There is no rush to set this thing up, I can play with the install of LUBUNTU on the old machine while I am studying things here.
You were able to do it with not a lot of trouble or so it sounded, but I think that "chance favors the prepared mind" So I want to be prepared!
I'll look at YouTube and see if I find any more tutorials elsewwhere.
Thank you and I'll be in touch via the forum!