fresh install of programs (word processor, spreadsheets, etc)

(on edit: i use “the cloud” for nothing. i want MY stuff on MY computer…with a backup)

Start at C:/ Check the directory files.....delete as wanted. Then the next level and do the same time.

Caution, this could take a boatload of your time to get from top to bottom.

On a new hard drive in my new pc. Do fresh installations of updated software. Run your old computer on your home network along with your new computer and enable file sharing. You'll be able to see your old hard drive from your new computer and you could just drag over what you want. You can even, from your new computer, launch files that are on your old computer and have them load in RAM on your new computer.

When you see your old computer on the network and try to navigate to its hard drive, you'll be prompted for login credentials for your old pc.

You might want to consider getting a NAS (network attached storage) and move your accumulated data to it for back up. Then you can strip down that old PC into a souped up dedicated tool running legacy programs for special occasions.

And then also put the old drive in the new computer, assign it as D:/ (or whatever letter is free). Then you have still have all your files right there and you can clean up the crud on D:/ at your leisure. This avoids the complexity of setting up a network server, which isn't that hard but just putting the drive in the new PC as a 2nd drive is very easy. If you've never had your system on an SSD, you'd be in for a treat. Nothing makes a bigger difference in day-to-day performance than having an SSD vs. a spinning drive.

They don't look like much more than a small RAM stick, but they are extremely fast and very well-suited to be the system C: drive. If the new system accommodates one, it's the way to go. I would go for at least 1 TB and 2 TB if you're using OneDrive (for files you're keeping on the PC in addition to OneDrive).

Now and then, I'll move my picture, document and download directories (which many programs use as defaults) from the internal disk over to an external drive.

The external drive(s) can be sneakernetted to another computer, or just shared via the network, and an old computer can serve them up just fine, especially for old files and directories you don't use that often.

I count three drives on the newest computer, including one terabyte of a 4 TB drive designated for incremental backups of the internal drive.

I got a new system, plugged in a couple of drives with the goodies, and was in business immediately, and the internal drive is pretty clean.

HTH

existing 1 Tb SSD into my new system. I really appreciate your help.

And this is a really good idea and can be a lifesave:

Partition your hard drive into:

1. Operating system and programs
2. Your own stuff

Reformat and reinstall the most recent version of windows you have or can run on what will become your C drive. Check your current system and programs folders for size to give you some idea of how large the partition should be. I'm good with about 300 gig but if you run some huge games and programs you may need more.

The other 700 gb or so becomes your own personal stuff. There are ways to move the built in users folders onto this drive via....
User Folder
Properties
Location - set new location on your new D drive

Once you have done this, a big clean out and reinstall of a bloated operating system becomes a breeze - something that can be done in a couple of hours, including program installation. Your own personal stuff remains untouched through the ages!

... and emulators for most of the computers and calculators I've used.

The first serious operating system I used was BSD. My all time favorite computers were the Atari 8 bits. The last Microsoft operating system I used on my home computers was Windows 98SE. I have about 40,000 photographs. I also have MP3s of my entire CD collection.

One of the reasons I switched to Linux was that it makes upgrading to a new computer easy. Once I've got the new machine running It's almost a drag-and-drop. I don't have to re-install or re-register any proprietary software.

My old proprietary Atari, MSDOS, and Windows stuff doesn't know it's running on emulated machines on new computers. Getting that stuff to work was a one-time problem.

The growth in hard drive capacities has easily kept up with the growth of my data hoard. It's simply not worth my time to sort anything.