Additional Study Information: The overall purpose of this research is to treat diseases that are not cancer but are improved by bone marrow transplantation with mild and safer chemotherapy as pretransplant conditioning. This treatment is chosen because it is milder and is likely to have fewer long and short term side effects unlike older chemotherapy and radiation treatments. Yet, it should allow donor cells to settle and grow because it has the necessary effects that will allow your immune system to accept these donor cells. The donor cells used will come from one of the following sources from a normal donor: bone marrow or umbilical cord blood cells. Who the donor is will be determined by who is the best available match to your tissue type.