 RATIONALE: Giving chemotherapy and total-body irradiation before a donor umbilical cord blood stem cell transplant helps stop the growth of cancer cells. It may also stop the patients immune system from rejecting the donors stem cells. When the healthy stem cells and natural killer cells from a donor are infused into the patient they may help the patients bone marrow make stem cells, red blood cells, white blood cells, and platelets. Giving interleukin-2 IL-2, aldesleukin after transplant may stimulate the natural killer cells to kill any remaining cancer cells. 