 Patients receive cyclophosphamide IV over 2 hours on day 0. Patients then receive clofarabine IV over 2 hours and cyclophosphamide IV over 2 hours on days 1-3 and 8-10. Treatment with clofarabine and cyclophosphamide repeats every 28 days for at least 2 courses in the absence of disease progression or unacceptable toxicity. 