I just installed PS CS4 to my new Windows 10 PC. I chose a different location than the default C: install location. Right after the installer reported success, my PC froze – had to restart using Ctrl-Alt-Del. When I looked at the install folder, the new PS folders were there, but all the other files and folders in it were gone. I had to re-install seven programs. PS appears to be working properly.
Just thought I’d post my experience as a warning to anyone attempting anything similar. There’s always the chance that old software might not work on a new PC, but I’ve never seen an installer do anything this destructive to existing files.