Fludarabine, Cyclophosphamide, and Rituximab Versus Pentostatin, Cyclophosphamide, and Rituximab in Previously Untreated or Treated B-Cell Chronic Lymphocytic Leukemia Patients

The purpose of this research study is to find out what effects (good and bad) the combination of Nipent+Cytoxan+Rituxan has on CLL cancer compared to Fludara+Cytoxan+Rituxan. While all of these drugs are approved by the Food and Drug Administration (FDA) for the treatment of other cancers, these combinations are experimental for the treatment of CLL.