I could be wrong, but I don't think you can dual boot minix3. Also, I believe minix3 can handle a maximum of 4GB of disk (I could be wrong, so don't quote me, but that seems to be standing out in my mind).
I'd recommend installing it in qemu or something similar.
i wanted to have minix to play around with the OS and see what its about. but i am having problems of minix freezing up when i install it or telling me i dont have enough space. and you say that minix3 can only handle up to 4 gigs of space?