Patients receive fludarabine IV over 1 hour on days -6 to -2 and melphalan IV over 15-20 minutes on days -3 and -2. Patients undergo allogeneic peripheral blood stem cell or bone marrow transplantation on day 0. Patients receive oral tacrolimus twice daily beginning on day -3 and continuing until day 100 followed by a taper to day 180. Patients also receive methotrexate IV on days 1, 3, and 7. Treatment continues in the absence of disease progression or unacceptable toxicity.