Here's a little tidbit I've discovered, which should help those of you make something of this "storage starved" box.
There is a 32 pin DIP pattern just to the right of the ROM. This appears to be present to allow for a M-System DiskOnChip DIP part to be put there. I populated the socket with a 32 pin DIP socket, put in a 8MB DOC (DiskOnChip) that I had lying around [that was setup to be DOS bootable], and sure enough I was able to boot. You'll need to do 1 of 2 things: either when you create your DOC image you specify /FIRST (so that the DOC is the boot drive), or go into SETUP and Disable the Primary IDE channel. I did the latter, since my DOC image was already created. Otherwise it will still try to boot off the SANDISK.
Works like a champ! Now you can get however big a DOC is these days (something like 288MB)!
PS: I believe the patterns under the DIP socket, and on the other side of the board, are for soldered down version of the DOC. This would allow for two 8MB parts to be soldered down, yielding 16MB total (same as the on-board SANDISK). Seems to make sense...