The subject will be given a drug called Ara-C in high doses through the central line every 12 hours starting 8 days before transplant (called day - 8) until 5 days before transplant (called day - 5). Starting one day after receiving the first Ara-C dose (day - 7), we will add a drug called cyclophosphamide once a day to the treatment for the next two days. This will be given in high doses (also through the central line). Also on day - 7, we will add a drug called MESNA. MESNA is used to decrease the side effects caused by cyclophosphamide. After the medication treatment is finished (day - 4), radiation treatment will be given to the entire body twice a day for 4 days. The chemotherapy and radiation treatment will last 8 days. If the subject has abnormal cells in the spinal fluid, 6 extra daily doses of radiation treatment may be given to the head. This would be done before any of the drugs are given and before the subject is admitted for transplant.