Another treatment option called immunotherapy is being tested in lymphoma patients. Immunotherapy involves attempts to use the immune system or products of the immune system to fight lymphoma. For example, NHL cells have a protein called CD20 on their surface. Rituximab is an antibody directed against the CD20 protein, which may result in the death of the lymphoma cell. Patients in this study will receive Rituximab to see if it is a safe treatment option for NHL patients.