This study hopes to learn if giving intravenous (IV) busulfan with fludarabine before (as a conditioning regimen) allogeneic hematopoietic progenitor cell transplantation (HPC) is safe and helps patients with Non—Hodgkin´s Lymphoma (NHL) and Hodgkin´s Lymphoma (HL). An HPC transplant takes cells from a donor´s bone marrow and, after chemotherapy treatment with a conditioning regimen, infuses the donor´s cells into the patient´s body. Busulfan is a strong drug that suppresses the immune system and fludarabine is a chemotherapy (cancer fighting) drug. These drugs can stop the growth of cancer cells by breaking the Deoxyribonucleic acid (DNA) or genetic material which is necessary for the growth of both healthy and cancer cells. The use of IV busulfan with fludarabine as a conditioning regimen prior to HPC transplant is investigational (not approved by the Food and Drug Administration [FDA]).