answer:Let me just clarify, you plan on taking one of your 512MB sticks and putting in the 1GB your Mom had left over? If that’s the case, then I do believe it is possible. However, in order to verify that what you are doing is correct, you should ask your technician or whoever is going to be doing the change. Unless you are thinking of doing it; you should then call Apple care (they are always very helpful!) and ask them about your issue to get a first-hand answer to your question. :)