I just had a fun experience trying to install DOS 6.22 onto my PC. Unfortunately, I don't have any floppy drives any more, but I only had DOS on floppies. When looking around for another way to install DOS, I ran across:
http://newdos.yginfo.net/msdos71/
I found an ISO image of DOS 7.10, and installed it without any problems. And get this: It even detected that I already had Win2K installed and automatically set up the NT bootloader for me to dual boot!
I'm very impressed, needless to say. It's worth looking at if you still want to run any of the DOS based CNC programs like TurboCNC or CNCZeus.