wrote on 05.09.08 at 10:22:11:

......but how do you prevent that programs (usually games and demos) executed from the mounted floppy, overwrite the memory area where the virtual floppy driver is living. And more difficult how do you intercept direct calls to the floppy controller registers of programs (usually demo disks) that skip the OS for doing IO.

With a lot of cunning...  despite what others might tell you, it can be done :)  Not saying its easy tho!