RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Peripheral stem cell transplantation may allow the doctor to give higher doses of chemotherapy drugs and kill more cancer cells. Monoclonal antibodies such as rituximab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. It is not yet known if combination chemotherapy plus peripheral stem cell transplantation is more effective with or without rituximab for non-Hodgkin's lymphoma.