Additional Study Information: The main purpose of this study is to see how effective an investigational new drug (tipifarnib, the study drug) is to treat myelodysplastic syndrome (MDS). "Investigational" means that tipifarnib has not yet been approved by regulatory authorities such as the United States Food and Drug Administration (FDA) for use outside of clinical trials. You may stay on the study for up to two years, depending on how well you respond to treatment.