Emulators running under Linux

• MAME - Multiple Arcade Machine Emulator    
• PSX - the Sony play-station emulators
• GameBoy - the ninitendo emulator, you need the proms though
• Snes9x - the Super Nintendo Entertainment System emulator (KDE knes9x frontend)

• DOSEmu - the MS-DOS emulator under Linux is a no-risks affair
• WINE - the MS-Windows emulator under X-Windows
• VMware Workstation Pro can reliably emulate any Windows version in a box under Linux.
• codeweavers