 Instead of the high dose chemotherapy and radiotherapy usually given before a transplant, this research study uses a new pre-transplant combination of three drugs, Fludarabine, Anti-CD45 and CAMPATH-1H with low dose radiotherapy. Fludarabine is a chemotherapy drug while Anti-CD45 and CAMPATH-1H are antibodies against certain types of blood cells, including those which are causing this disease. CAMPATH-1H is particularly important because it stays active in the body for a long time after it is given, which means it may work longer to prevent GVHD symptoms. Anti-CD45 may help in eradicating residual malignant cells. All these agents also help in preventing rejection of donor stem cells. This study is designed to give a less intense chemotherapy and radiotherapy, so that the life-threatening toxicities of conventional high dose chemotherapy and radiotherapy regimen can be reduced, while maintaining the ability to cure cancer. 