 This is a study to explore the use of a reduced intensity transplant conditioning regimen. A conditioning regimen is the treatment that is given to prepare a body for the new bone marrow that will be received from a donor. Reduced intensity conditioning uses lower doses of chemotherapy than conventional conditioning regimens. The use of lower doses of drugs and radiation cause fewer side effects. Reduced intensity regimens have been offered to older patients or patients at increased risk for transplant-related side effects and have been shown to be safe and effective. Reduced intensity conditioning regimens are now considered for many patients who are undergoing transplant. 