@crawff
As the Minimig only supports FAT16 and dose not support using directories at this time 2GB is the biggest partition you can access and it dose not have support for more than one partition on a single card as far as I am aware.
I am using a 2GB card on mine and that seems to be plenty at this time, If I get an arm add on board for hard disk emulation at some time in the future then support for larger cards would become more useful.