i think i did the same thing Bionic_Flea - I moved the OS to C:\, Programs to D:\, and I use my E:\ for data documents, files, music with backups from there. I hate looking all over a file structure to find what needs to be backed up.
I am not a technical person, but I was surprised how easy it was to install the SSD, clone the data and reuse the old hard drives. The boot time - wow. New life in an old computer and even some things like copying files or working in Excel for my limited uses seems just faster.
My computer is probably 5 years old and I would really like to keep it on Windows 10 for a couple more years before I invest in new hardware, new Windows 11. I think it might be my final desktop before I make the jump to a laptop for everything.