yes that is correct. the 256mb is soldered on, leaving only one available slot to add additional memeory.
how much memory are you thinking about adding? i just bought a used ibook and it came with 256mb, i had another stick of 256mb from my old windows laptop, so i put it in and it runs great. there have only been a few times where i have gotten the beachball. so depending on what your daughter is going to be using it for you can probably save some money if you want and just use lower sized memory. then again you can max it out to 1.25gb.