Important folders to backup from C-drive before cleaning it up

Snick said:

Thanks for the info
Personally, I'd keep the old one and upgrade to win10x64 pro, full disk image of the new one on ext HDD, and give sis the new one minus your files of course.

Are you suggesting I should keep the Computer 1, upgrade to Windows 10 64-bit Pro, full disk image Computer 2 to extHDD and give my sis Computer 2 minus my data?
Or are you suggesting the exact opposite?

Snick said:

on the backups.

Thanks, I'm pretty sure, you use some fantastic techniques.

Snick said:

Questions:

1. What do you have on your 4TB drive that is so filling?
2. Is everything compressed?
3. How often do you backup your computer?
4. What type of backups do you do?
5. Full disk image?
6. Incremental?
7. Differential?

Answers:
1. 4-full system backups, 3 incremental ones, lots of tutorials, RAW photos and videos, gathered over the span of 10 years.
2. Backup images are, rest are in simple browsable format.
3. Full system, aka, cloning, once in a month; incremental, once in 3 days.
4,5. Full system for when I hit first basic setup with everything working, and stable setups for every month.
6. Incrementals in between setups where I might try something that can absolutely wreck my system.
7. Never tried that, is it advantageous over others?


EDIT:

By 4 full system backups and 3 incremental ones, I mean, I keep one full system backup (first setup), then 3 full system ones for last 3 months, and their corresponding incremental ones for last 3 months which are spaced by 3 days each.
I hope this clears up the confusion.

Don't have your complete system specs for both computers but it appears as through your old machine is more capable.
Here's a tool that you can use to collect your specs in a text file on your desktop. Download and double click to run it. BTW: you can right-click, choose edit and see the simplistic code.
SysInfo to desktop.bat
Or a description of each would probably work. Then we can Google, compare the age, make, motherboard, processor, we already know the ram and HDDs as you stated.
Big thing to me is the 64-bit and more ram, larger hard drive usually equates to better motherboard, processors CPU/GPU, etc.

OK, makes sense to me now & sounds like the right move for you two too.

Nothing special, I do a full disk image of both computers with AOMEI once a week on Sundays (check image integrity always). Usually keep newest 2-3 of each Drive.

Here's some good info on AOMEI Incremental VS Differential Backup - AOMEI Backupper
Video AOMEI Backupper - How To Make Incremental / Differential Backup ...
I don't make incremental or differential backups due to the complexities of trying to restore from them. It's not quite as easy as from a single image. IMHO