This revised transplant protocol will test the following: 1) the ability to achieve engraftment with the reduced intensity protocol and a second infusion of stem cells on day 42, 2) the mortality associated with transplant by day 100, 3) patient outcomes, based on differential imaging and biologic evaluations prior to transplantation and at designated points after transplantation (day 100, 6 months, 1, 2 and 5 years). Additional biologic studies will include microarray analysis, and evaluation of blood parameters and genes that may be important in the disease process. In older patients, studies to evaluation osteoclast differentiation and function will also be offered.