If usermade levels are possible, this thing can hold up to 8 (perhaps 16) GB of levels, as that's the largest size of a mini SD card. (in 2011, this is expected to be 128 GB according to Sandisk). The levels don't need to be loaded immediately into virtual memory, that can be done when needed. In virtual memory you can, of course, store way less. Can't remember how much exactly, but not a whole lot.