I had a HDD replaced with a SSD in my desktop computer and some the files from the old drive were transferred to the new drive (I think the OS was left on the HDD). I'm now looking at buying a new desktop and deleting unnecessary files from my old computer.
I can see that I have my OS in my C drive and other files in my D drive and I went to delete some files and it said they were 'system files', so I left them. I can see I have a 'Users' folder in my C drive and another one in my D drive - this is were some the old files from the old drive are located.
How can I tell what is important and what isn't?
Thanks.