GROUP A (no planned peripheral blood stem cell [PBSC] support): Patients receive rituximab IV over 4-6 hours followed by indium In 111 ibritumomab tiuxetan (IDEC-In2B8) IV over 10 minutes on day 0 and undergo whole body imaging. Patients may then receive rituximab IV over 4-6 hours followed by IDEC-Y2B8 IV over 10 minutes on day 7.