VirtualXT is a core emulator that runs on modern hardware and operating systems. It is designed to be simple and lightweight yet still capable enough to run a large library of old application and games. The default setup emulates a CPU running at 4.77 Mhz just like the original. This is quite a slow system and the original one only operates in real-mode. This means that no protected-mode or 32 bit applications will run. (Most software from the 90's requires a later CPU.)
RetroArch is free/open source software, available under the GNU GPL 3.0 license.
It does not contain any copyrighted material by third parties. RetroArch does not condone piracy in any way, shape or form.