Patients in this study will receive 6 cycles of combination chemotherapy with the standard CHOP regimen given in conjunction with rituximab. Cycles are repeated at 21-day intervals for six to eight cycles. Patients achieving at least a partial response to chemotherapy will begin PEG Intron at a dose of 2g/kg/week subcutaneously. PEG Intron treatment will be continued for 12 months in the absence of signs of progressive/recurrent disease, or unacceptable toxicity/intolerance of therapy. PEG Intron dosing will be adjusted based on the presence of symptoms or other clinical manifestations of toxicity. Patients will undergo bone marrow evaluation for molecular testing at baseline. Those found to be positive will have repeat assessments performed post induction therapy, and after six months of PEG Intron. Patients will also undergo immunologic evaluation at baseline, post induction therapy, and after six months of PEG Intron. At the end of PEG Intron therapy, patients will have disease reevaluation and then annual data collection for long-term toxicity, duration of response and survival.