DosBox is a DOS operating system and hardware emulator, that allows users to play old Dos games on their modern computers without the usual trouble. The games will work with normal speed, since the user has full control over the CPU cycles used by each game.
Since DosBox comes with a Sound Blaster and General Midi emulator - the sound effects and music on old Dos games will work even better than they were meant to work on the old Dos-based computers - since the sound and and music will be played on today's high-detailed sound cards and speakers.
All and all, DosBox is just what you need to get those oldies back up and running (without any special patches that are supposed to fix CPU based or soundcard based problems!).