Everything is working nicely now, thanks for the help and suggestions.
I installed 8 first, then 2015. I can just double click on a model if I want to open it in 8 (I still save all my work as 8, for various reasons), or just right click on it and select Open with Sketchup 2015 when I want that.
I use my C drive only for the OS and programs, so I wasn't worried about all my Sketchup stuff (actually that's what it's called, Sketchup Stuff, my largest folder, 265GB, 347,927 files, 9,769 folders) or anything else, just some of the stuff on my Desktop. I had some folders there that would have been almost impossible to rebuild from scratch, plus there was my Thunderbird Local Folders file (144 local folders). I was really lucky to find a program that let me recover all that stuff.
I guess I was getting complacent, I never had a hard drive crash so completely like this one, I was always able to pretty easily save the files I needed when a drive started going South. Now I include such files in my backup plan.
I tried a number of backup programs before I found Syncback Pro, been using it for years now and it works really great. I can setup a new profile in a minute or two. I too use a 1TB WD black for my backups, only connected to the computer when I do my backups. I also regularly backup to my backup computer, which also has a 1TB WD Black which is connected when I do backups. Plus, everything is backed up to my laptop.
So I think I'm pretty much covered there. Backups of my backups everywhere. Yeah, I are a bit paranoid. I never have more that one computer connected to the internet at a time, and only when necessary (I only use hard-wired modems and routers, and I have them connected to the AC through remote controlled outlets, so I just click a button to connect to the internet and click again to disconnect, no sense giving the bad guys any more of a target than I have to ๐ )
I might give an SSD another try eventually. I've been eying the Samsung 850 Pro 512GB (MZ-7KE512BW), not cheap but looks promising. Maybe I'll just let the technology cook for a couple more years.
Anyhow, thanks again for the help. Much appreciated