RATIONALE: Giving chemotherapy, such as fludarabine and melphalan, before a donor peripheral blood stem cell transplant helps stop the growth of tumor 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 tumor cells (graft-versus-tumor effect). Giving an infusion of the donor's T cells (donor lymphocyte infusion) after the transplant may help increase this effect. Sometimes the transplanted cells from a donor can also make an immune response against the body's normal cells. Giving antithymocyte globulin, cyclosporine, and methotrexate before or after the transplant may stop this from happening.