Fludarabine and Busulfan Followed by Donor Peripheral Stem Cell Transplant and Antithymocyte Globulin, Tacrolimus, and Methotrexate in Treating Patients With Myeloid Cancer

RATIONALE: Giving low doses of chemotherapy, such as fludarabine and busulfan, before a donor peripheral stem cell transplant helps stop the growth of abnormal and cancer cells. It also stops the patient's immune system from rejecting the donor's stem cells. The donated stem cells may replace the patient's immune system and help destroy any remaining abnormal or cancer cells (graft-versus-tumor effect). Sometimes the transplanted cells from a donor can also make an immune response against the body's normal cells. Giving antithymocyte globulin, tacrolimus, and methotrexate before or after transplant may stop this from happening. PURPOSE: This phase II trial is studying how well giving fludarabine together with busulfan followed by donor peripheral stem cell transplant and antithymocyte globulin, tacrolimus, and methotrexate works in treating patients with myeloid cancer.