The purpose of this study is to determine the tolerability and efficacy in treating patients aged 51-60 with acute leukemia and in treating myelodysplastic syndromes (MDS) or myeloproliferative disorders (MPD).

To learn whether a new preparative regimen to prepare patients for bone marrow transplantation is useful in patients above 50 years of age and whether it is useful in patients with myelodysplastic syndromes.

Inclusion Criteria:1) Patients aged 51-60 with acute non-lymphocytic leukemia in first or subsequent remission and acute lymphocytic leukemia in first remission with high risk features which include elevated white blood cell count at presentation, cytogenetic abnormalities, extramedullary leukemia, ALL in greater than first remission and patients with chronic myelogenous leukemia at any stage who have a histocompatible sibling donor.

2) Patients with myelodysplastic syndrome including patients with refractory anemia with excess blasts or refractory anemia with excess blasts in transformation.

3) Patients with myeloproliferative disorders which give them poor long-term disease-free survival, such as myeloid metaplasia or myeloid fibrosis.

4) Patients with secondary myelodysplasia following cytotoxic chemotherapy. Exclusion Criteria:- Organ dysfunction