As far as I know (ie I dont own monkey madness) it doesnt have the audio setup bit that the white label version does.
To hear sound you will need to have dos sound emulation active (assuming you have 98 98 or ME) and you might simply need to start it with a command line. See here
for more info on things you can try and for starting with a command line (yes I'm too lazy to retype).
If you switched to XP ---- yes and no.
If you used LEC Quick and Easy then MI2 would work fine with sound however MI1 would probably develop the annoying "Cd audio sync problem". On the other hand this can be fixed by making a cd image of the monkey madness cd and mounting the image in daemon tools. You may not have the cd sync problem (so far I havent heard of anyone else having the problem with Q+E it may just be me).
So things would get both worse and better
Computers eh? Dontya just love em?