RATIONALE: Giving chemotherapy before a donor stem cell transplant helps stop the patient's immune system from rejecting the donor's stem cells. When the healthy stem cells from a donor are infused into the patient they may help the patient's bone marrow make stem cells, red blood cells, white blood cells, and platelets. It is not yet known whether donor stem cell transplant is more effective with or without chemotherapy in treating primary myelodysplastic syndrome.