The legality of downloading a lot of these games would be questionable however. Even though it's unlikely that the company that made them is making any money off of them any longer, they are still covered by copyrights for insanely long periods of time.
You could probably find loads of these things on ebay. Like all the classic Doom's, and the first two Quake's. That's where I'd look personally. For a relatively small amount of money, you could probably come away with a large number of classic games.
Where can I download computer games that will run on old Celeron366 computer.
Do anyone have a website of old games from around 8-10 years ago.