RATIONALE: Drugs used in chemotherapy, such as pemetrexed disodium and cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed. Giving combination chemotherapy after surgery may kill any tumor cells that remain after surgery. It is not yet known whether combination chemotherapy is more effective before or after surgery in treating non-small cell lung cancer.