If you are between the ages of 1 and 80 years old (and the study doctors think this would keep you from receiving the full myeloablative therapy), if you cannot receive low-dose total body irradiation, and if your doctor agrees, you will receive fludarabine-melphalan-ATG. Starting on Day -5 you will receive fludarabine given once a day for 4 days in a row (Days -5 through -2). You will receive Melphalan as a single dose on Day -2. You will receive ATG on Days -3 and -2. Day 0 is the day of transplantation.