Knock it off or this gets locked.
Dosbox will let you play old DOS games with decent compatability if not near perfect emulation.
As for older windows games, you can either pirate them (don't ask us where to get them) or find them for sale from a trusted source. As far as playing them, there is no real emulator for that, you have to find a compatible OS that can play them, sometimes that means dual-booting with an old OS and your current one. It can be a lot of work to set up, but if its worth it to people they don't mind once they learn how.
There Is a project called ReacOS that aims to be a Win32 clone, compatible with all the programs you can run on Windows, but using open source code. It's got a LONG way to go before its viable, and even basic DirectX support is likely many years away based on their rate of progress.
Here is the web site,
http://www.reactos.org/en/index.html
Obviously, its still in Alpha stage but I hope one day it will be pretty viable for an old gaming platform