In some of the earliest Win versions, you had to get the "Plus Pack" to get Solitaire and Freecell - and a few other games. There were additional "Game Packs" that you could get fairly cheaply. Many OEM system disks included the Plus Pack stuff on the install disks, so the "where did it come from?" can be only vaguely known. It would be rare, though, to find a Windows installation that doesn't have those two games, and probably Tetris, unless some malicious system administrator deliberately removed them - presumedly on an office machine setup.

Most of the old games will run on any Win version just by copying the files, although a few of them have some "associated files" for things like scorekeeping that should be brought along.

Some of the oldest ones may be "unfulfilling" run on newer machines. The original Solitaire used a simple "clock-cycle" delay in the "falling card" display when you won a game, so on a faster machine it may be "just a flash." The "reward" display was retimed for Win98, I believe, and an "undo" button added at about the same time to let you back up - one move only. The default Solitaire setting is to "turn over the pile" 3 cards at a time. All versions have allowed (for program testing purposes only, of course) using Ctl-Alt-Shift held down while you click the turnover/deal to turn one-at-a-time: but don't use it to cheat....

John