OUTLINE: This is a multicenter, randomized study comparing a chemotherapy only arm, including busulfan, with a TBI containing arm. Arm I patients receive TBI on days -7, -6, and -5 given in 2 fractions daily. Arm II patients receive busulfan every 6 hours on days -8, -7, -6, and -5. Both regimens are followed by etoposide over 4 hours on day -4 and cyclophosphamide intravenously (IV) on days -3 and -2. Marrow infusion begins following a day of rest. Starting on day -1, cyclosporine IV is administered every 12 hours or by continuous infusion and continues until day 50. Methotrexate IV is administered on days 1, 3, and 6